That's a weird goalpost to me. Because in story, everyone is already using male pronouns.
It feels like you're treating the character as a child, claming they're astronauts and that they go to the moon every night, and every "outside source" (editors, advertisements, etc) as a parent, nodding a No in the background saying "Oh, she just has a lot of imagination".
But the character is a capable and full grown adult making their decisions.
Yet, here's the thing: we can't ignore that Yamato is a One Piece character. Considering the setting, where fantastical humor, exaggeration, and allegory abound, one cannot completely discount the possibility that this will prove to be the case, on some level at least. Any attempt to view the One Piece world and characters through a realworld lens without the proper context is an exercise in futility. Hell, if we're to apply strict realistic standards to the One Piece universe, just think how many of these characters would be deemed guilty of child abuse, sexual harassment, etc? It's just not that cut and dry.
As has been noted multiple times, it's only further muddied by the fact that Oda has potentially directly tied Yamato's gender to her adoption of Oden's identity, thereby possibly framing her choice as mere byproduct of her decision; more so a technicality than a thoroughly informed personal decision independent of their desire to become Oden. One could even interpret it as Oda seemingly tying the topic of gender to the subject and heavily overarching theme of roleplay that's currently at play; a very controversial, risky narrative route to explore, to be sure, if such truly is the case, particularly as it pertains to Western audiences.
Now, is that truly Oda's intent? Who can say for sure? Like I said, it's just one possibility, as there's certainly more straightforward, clear-cut avenues Oda could've taken, as many would agree at this point. As others have mentioned, methinks it's best to let things play and and wait n see how Yamato's story develops before rushing in to "claim" Yamato as validation of one viewpoint or another. There's no telling with any sure certainty what Oda intended or what he's thinking so far as Yamato's character is concerned. It can go several different ways. And yes, one such possible scenario is that Yamato will go back to identifying as female upon realizing their admiration for Oden doesn't have to extend to very literal emulation. In terms of fictional characters, I think anyone who's read/watched enough manga/anime is familiar with the trope of a "masculine" biological woman eventually "re-embracing" their womanhood yadda yadda….it's an extremely cringy alternative, especially in light of the controversy, but it's not an impossibility, however remote. Like I said, best to temper one's expectations.
That said, that isn't what I personally see happening, or prefer to happen, mind you. Again, I can't guarantee anything and this is just my own speculation, nothing more, but if Oda sticks to the thematic path he's exploring right now ( imo ), what we may actually see by the conclusion of Wano is Yamato reaching an epiphany of sorts, as outlined in that scenario I mentioned above...only instead of declaring themselves as either male or female, in true colorful One Piece wonky fashion they'll conclude that they are male and female; both and neither at the same time, a perfect harmonious balance.
Of course, I'm sure that wouldn't settle anything and only open up a whole new can of worms. But then, an open-ended resolution that invites heaps of debate and varying interpretations is exactly the kinda route I could see Oda taking. But again, no-one can say for sure right now.