POST WAY LONGER THAN EXPECTED. Just typing as I'm thinking.
Yeah I definitely have it that Sanji is having Haoshoku Haki.
I feel like Oda will do it this way:
Notice in Zoro confirmed awakening Haoshoku Haki was simultaneously with Sanji speech about Germa mindless stuff.
I'd guess Sanji will awaken Haoshoku Haki in relation to his Germa Genes but basically his willpower overpowering the becoming mindless. Luffy awakening Gear 5 also came in Luffy appearing dead and mindless. In fact both Luffy and Zoro's came with Luffy apparently dead and coming back. Zoro reclaiming his bond with his swords. So Sanji will possibly come with a moment like that. Although technically that moment should have been the moment Sanji awakened it. Maybe it is but it isn't confirmed. And that wouldn't be off because it was presumed Zoro used Haoshoku before Sanji used Ifrit Jambe, and confirmed either after Sanji did so or around the same time. So technically in terms of Luffy, Zoro then Sanji, well it would still sync up that Sanji doesn't unlock the ability prior to Zoro. I think its hinted in the Wano battle that Sanji will overcome the Germa stuff to unlock a new power. If Haoshoku is the strongest ability so to speak, as Kaido said Haki is, then the whole warrior of Science speech. He said if he gave in he'd be many times stronger. His current way he'd be weaker. So now Germa genes are being presumed stronger than armament however very likely not Haoshoku. So my guess is Sanji will unlock the power that is stronger germa genes. And what did Sanji say, what does the pirate king need? Emotionless can destroy at will. Kaido said he can't have too many conquerors in his crew. Flashback to Rocks who technically Roger surpassed in becoming at least Pirate King, too many conquerors in Rocks. Rocks crew was merciless to each other, similar to what would happen if Sanji gave into the germs stuff, hence the Zoro conversation. So what does the pirate king need? Germa genes wouldn't be similar to Haoshoku in the aspect of Sanji would be of diminished willpower. Which Haoshoku is strong willpower. So it leads to saying that Luffy needs people who are Conquerors. Which indicates Sanji developing such. Also, if you notice when Sanji used Ifrit Jambe, what preceded it? Sanji turning invisible so to speak. What were we shown earlier? Use of Haoshoku Haki in the advanced levels basically an invisible barrier that doesn't require making physical contact. Seems quite another hint. Obviously Sanji high speed movement is just moving fast but the idea of what was going on itself is hinting the Oda saying haoshoku already exists in Sanji.
more on the Zoro and Sanji stuff. Basically people at this point because Zoro now has Advanced Haoshoku, will be presumed to be as strong as Luffy. Technically it is fair to presume. However Sanji asking Zoro to finish Sanji, I feel, is not because Sanji feels Zoro to be so much weaker. Technically it Zoro was his only contact and technically at the time the crew hierarchy is Luffy, Zoro and Sanji. Not an odd ask. Now Zoro said he could look forward to such a battle, meaning that Zoro considers taking on Sanji for real, as a challenge. Similar to maybe Roger asking that request of Whitebeard or Garp. And what was shown in Wano flashing back, Roger and Whitebeard shown as near equals and Roger making a request to Whitebeard. One in a similar manner to Sanji. Doesn't mean Sanji is Roger and Zoro Whitebeard. I've used examples using different characters. But basically you could say
Luffy is Rocks. Zoro Roger Sanji Whitebeard.
Or Zoro Roger and Sanji Garp. It would take both Zoro and Sanji to defeat Luffy. Sanji closer to Zoro than Zoro is closer to Luffy in strength. Though it fluctuates and sometimes Zoro is closer to Luffy in strength and sometimes closer to Sanji in strength.
Ultimately if you base it on powerups well,
Sanji did lose the Raid Suit apparently, which in conjuction with the exoskeleton is a power up similar to Zoro having Enma, Zoro being able to exert more Haki and also use Advanced Haoshoku. I'm not saying they are equal powerups. Technically if I had to say Zoro really got 4 or 5 powerups.
Enma - in itself claimed to have Oden's essence
Enma - Drawing out extra haki, cursed blade aspect
Conqueror's Haki use
Advanced Conqueror's Haki
Sanji got the raid suit and destroyed it. So where Zoro lost Shisui and got Enma, Sanji got the raid suit then lost it. So that reverts him back to Whole Cake Island.
But he develop an exoskeleton, speed and regeneration. Now most people would say well that is 3 powerups. But consider this,
Luffy's Gear 4 (Boundman by itself) gives him enhanced speed and defense. That isn't treated as multiple powerups. So technically he really only got one powerup that he used to make Ifrit Jambe.
Now technically the healing comes from Germa but speaking of Gear 4, the other influences of Sanji's ability are probably
Vergo and Doflamingo.
Vergo - Mass of steel
Doflamingo - Regeneration internal organs and overheat. He was about to use overheat on Sanji and although he didn't use Regeneration when facing Sanji he had the ability. More on this is probably the Black Maria trap compared to the Doflamingo strings mixed with Boundman enhanced Haki breaking the strings, as well as Fujitora showing that the parasite string could be prevent with CoO, Sanji specialty. Just saying to indicate that more than the Germa ability influenced this power up. Because most people will say it is just a cheap addition but it matches the Sanji picking up enemy abilities. Just like he got Sky walk and Blue Walk because he fought Jabra who used Geppo and Soru on Sanji in mid air right before Diable Jambe.
But really he is still behind on the power ups here.
Luffy got the use of Ryou (shield version and internal destruction)
Luffy got Advanced Haoshoku
Luffy got Gear 5
Plus he already had multiple forms of Gear 4.
Then advanced usage of Gear 2 and 3.
Haki
Luffy armament coating
Zoro was given
Haki, armament coating, New use of Haki through sword, Haoshoku Haki, Advanced Haoshoku Haki, enhancement of techniques
Sanji was given
Haki, no use of armament coating, same diable Jambe, exoskeleton, ifrit (from exoskeleton), basically nothing special about him having CoO.
I'd say Oda owes Sanji a powerup two here. Based on Sanji opponents well his latest ones were basically: Page One, X Drake (since the brief Doflamingo clash shows Oda still incorporates abilities of brief opponent clashes, which again isn't ridiculous as Oda had Luffy develop gear 2 off his brief encounter with CP-9), Queen, and briefly King. Technically my guess is the flame of Ifrit Jambe aspect also comes from King as well. Technically there isn't anything Sanji can incorporate from these Zoans as their abilities are raw power basically. I'd say from another aspect from King is maybe he'll have the ability to send projectile fire, hence the reason Sanji also just faced seraphim Jinbe. As Jinbe fighting style includes water projectiles. Possibly another reason Oda had Queen do the rocket launcher. Proceeding Sanji power up. Oda showed Zeff using force of his kick to blow out fire, so my guess is the enhancements will allow Oda to justify Sanji having long range ability. We saw Marco, who has blue flames (Pearl used blue flames) use a projectile or shockwave. And of course Sanji has Blue Walk, and Sky Walk. Blue Walk in sea relating to Fishman ability like Usopp mentioned. Sky Walk, relating to Lunarians. Sanji ran so much he ended up Flying. Lunarians were atop the red line and apparently on brink of extinction at least one ended up fleeing to the ground (since there were reward for them it is probably presumed some escaped, based on something that crossed my mind, the reason for Crocodile high bounty may be secretly that but Oda is hiding it for now). So Blue Walk and Sky Walk (along with Lunarians from the sky) which have seem pretty useless fighting wise as Sanji's main power ups possibly hint to connect Sanji eventually having projectile flames. Plus Blue flame Marco is also regenerative although Sanji wasn't an opponent of him. But yeah technically none of Sanji's opponents since WCI have any adaptable abilities. Though the the First Jambe influence may also come from Oven, and extra defense ability from the Zoans. With King having the slicing wings attack, although he used it on Zoro, that may also become a thing for Sanji, flaming slices. And I guess if trend follows Oda may give Sanji the future sight stuff for the Katakuri run it. But maybe Oda should expand some more one the uses of CoO. No offense as future sight stuff does work in Mangas. But Luffy already has it. Different from having advanced Haoshoku. Possibly having more used besides Future sight and Shanks type. I don't know what he could develop but definitely a worthwhile powerup in it. Oh and the brief Big Mom thing seems to also be an Ifrit Jambe influence as well. Prometheus - Fire and Zeus - Lightning. (Also the electromagnetic crack Judge). Which again because of Napoleon, and her showing the whole using Napoleon with fire, well that means that Sanji will likely be able to do flaming slices. And plus Big Mom had the ability to regenerate although through using souls. And she was able to expand in size. That would be Yonji which ability enhancing his strength. And I guess the soul ability Big Mom has will be his influence over Conqueror's Haki.
Rayleigh said to improve Conqueror's Haki you have to clash with strong Haki users which Big Mom is an Advanced Haoshoku Haki user. So technically because of Sanji being one of the main fighters and not like Brook, as Brook is more Koala or Hack (under a commander), that clash may just be a pre-cursor to the conqueror's Haki stuff. So weird people really don't consider Sanji worthy. Especially in a case that was certain doom for Sanji. Even Nami's mention of the half the crew missing facing off in whole cake island would be certain doom. Anyway, it seems there are plenty hints to Sanji, developing power ups. The further hint of this is, Queen is a cyborg who modified himself based on the Technology related to Sanji. And gained abilities of all the Germa. And Queen rivalry with Sanji father. Opponent so to speak. Basically incorporates the abilities of his opponents matches Sanji. You can also see this in Zoro learning Kin'emon's attack even though Kin'emon is an ally. Zoro from the ally, Sanji from enemies. So I guess partially another no Sanji rooftop thing is because in this particular case Sanji already came across Kaido abilities in Big Mom, Page One and King. As they were all before the rooftop. Lighting, Fire and potentially the cutting attack Kaido has is similar to King and the Ancient Zoan durability. Luffy seems to have gotten Red Hawk from ally Ace but also learns from enemy abilities, showing him being a combination of how Zoro and Sanji each get their new abilities.