It's interesting because I'm fairly convinced that the newkama plot is just the pre-timeskip introduction/metaphor to something we'll soon see in the manga: transcended/evolved humans. It's not about gender, but about the union of male and female souls within a body: Yin/Yang, the importance of the panda motif, the duality/mirror aspects and so on.
It's about alchemy and that type of folktale, with hints of it already sprinkled in the manga: the el dorado/philosopher's stone lore, the pentagrams we now see associated with the devil, the scientist that postulated the weight of the soul. Ivankov is the "king of queens", the "miracle worker", with a power capable of altering the human body.
Remember Inazuma? He was someone that Ivankov mentioned as being "very important", with a Harry Potter scar and a half/half visual, alternating between male and female body types. He was given an importance that was never elaborated on, and why's that? Because we're not quite there yet.
I mentioned this flashback relating to Germa but that's mostly figurative - Germa was the warmongering nation that people feared, had great power and influence that ended abruptly, associated with the devil, eventually had a weird relationship with nobility/government -> we see them as mercenaries in present times, just like the giants were called by Sommers. Is that all? No, we also have the connection with Big Mom, the marriage plots with Loki/Lola and Sanji/Pudding and the lineage factor and discovering the "blueprints to life itself".
We're at a point where all narratives start converging.
Edit: Oh, and you needed 5 years to produce a 20 year old germa clone, or something along those lines, so relative lifespans being another common plot point like the one mentioned with Harald and the 15/45yo stuff.
