So, the core of my problem with the Tama situation, like many things in the Wano arc, is that it doesn't feel earned. -A story is supposed to make you feel things, so long as it isn't disappointment or boredom.
-The good guys have to struggle and overcome in a story.Last chapter, Oda showed us that the heroes are totally, royally screwed if things stay the way they are. This is good, it makes the reader feel anticipation, tension. We want to see what awesome development turns the tide. Do the straw hats cleverly reveal a trump card? Does an awesome character we want to see show up?
Oda then follows it up with this chapter. He wants us to feel hype, relief, as if we want to cheer Tama on for saving the day. But I just feel disappointment and like I'm cheated by the story itself. This isn't a satisfying way to relieve the tension. The heroes didn't earn this, the perfect power fell in their lap, and instantly voids a plot point that was built up for a long time as important. And if it's not earned, at least relieve the tension with some awesome, hype development. Even a really hype character showing up as a deus ex machina would be better than this. At least I would feel something better than being cheated or disappointment.Here's one easy way to fix it: those among the samurai resistance who were familiar with Oden and thus knew about the outside world, maybe some scabbards among them too, knew about this fruit. They actively sought this fruit out because they knew it could turn the tide against Kaido. They went on a long journey to get it. Either they gave it to Tama or she ate it not knowing what it is, for a funny scene, queue the face faults. There, now it at least feels earned. Now it was actually part of the heroes plan. It's not perfect, but it's an easy solution some rando on the internet quickly came up with.
The problem with post-timeskip One Piece is that Oda juggles a million billion plot points and characters, which he can never all flesh out and give time to breathe. As a result, we haven't gotten invested yet and things just don't feel earned.
This is a complete crap argument when you realize Act 1 was literally about Luffy rescuing Tama, bonding with her and learning about the intricacies of her ability, after the enemy failed to steal it for their own purposes. Luffy put Kin'emon's plan at risk in order to do so and was rewarded for it.
Meaning that, yes, Luffy earned this power. He inspired Tama to participate in the war.