Watched film Red recently and anyway AU where after abandonning Uta in Elegia, Uta manages to convince Gordon that 'hey living on a island where everyone is dead is not the best place to raise a kid' and due to a convoluted plot that can only be made by an actual child, they move to Dawn Island.

Anyway this'd be after Shanks last visit there but before Garp moves Luffy to the forest so Luffy is like :D Uta you're not dead (because him and the village totally assumed "she's in a better place to learn to become a musician" meant she died, yeah.)

They probably get into a fight over the fact Uta now hates Pirates and especially Shanks (and refuses to admit she feels jealous and mad over the fact Shanks left Luffy his hat and a dream, when he didn't even say goodbye to her), soon after Luffy is sent to the Bandits, and Gordon finds a job as a music teacher in High Town.

Time passes and Uta forgives Luffy even if she still hates pirates, they probably met a few times but she doesn't truly reconcile with him for a while (maybe after Sabo's "death"?). Ace and Uta hates each other at first but find an agreement in the mutual hatred of their father for choosing piracy over their kids.

When he set sails, Luffy invites her to join his crew. She refuses.

Gordon and her are pretty popular in High Town as music teacher/musicians, despite being outsider. Being from Elegia does bring some prestige, even if the island doesn't exist anymore. They're not part of high society but the nobles being able to invite them as musician for a party is seen as a sign of idk being rich or something.

I guess she still becomes the one piece equivalent of a youtuber but instead of planning to change the world and destroy piracy or something, she ends up somehow joining the Revolution Army. Not so much as an active member, but maybe more the kind that goes around everywhere and brings information and contacts. (I don't have the details in mind though - anyway she does meet Sabo there, but since he doesn't recognise her she just assumes he decided to abandon Luffy and Ace. She never finds out about the whole Amnesia thing - or if she does it's after he gets his memories back. Her abandonment issues are off the charts.)