Luffy was clearly always fated to be PK, the fruit and joyboy stuff isn't really anything new. He has the will of D, conquerors haki, the voice of all things, has the same dream as roger, brothers with ace and inspired by shanks, has rigers hat, grandson of one of rogers greatest rivals, supposedly fated to destroy fishman Island, etc. The thing is though, luffy is also just doing it cause he wants to, even if he knew of his fate, it wouldn't change how he lived his life, nor would his life change if fate wasn't a part of it. Its like how in real life, we're "fated" to die, but that doesnt mean we don't have control over what happens in between then and now, everything luffy does until the exact moment he becomes pk (and maybe some other major events, like liberating certain countries), come from his own choices imo the problem with the naruto one is just that the og naruto was all about defying fate, whereas it made a complete 180 to being all about fate, just like how Shinobi fights were supposed to be all about intelligence and tricks, and then became about 100ft chakra avatars throwing laser beams at each other