Been keeping an eye on this for reasons. Not that I would EVER do something so ILLEGAL as to pirate a game 4 days early and then want to migrate the save to the official PC Game Pass version once it's actually available. I would never suggest anyone do anything so absolutely horrible to the really struggling indie game company Microsoft because that would be breaking the law, and of course nobody should EVER break the law.
But if anyone did that anyway and realized that they couldn't move their save between their completely unconscionable illegal copy of game to the legitimate version that they paid for but had to wait an additional 5 days to play because reasons, there's a utility to do it now.
https://github.com/HarukaMa/starfield-xgp-import/releases
I can't speak to the validity of it from a like, virus perspective, although the source is all right on github and it looked fine to me, but verify for yourself anyway. I can say that it seems to work though. I read one person say that they got banned from a different game years ago for editing their game pass save too so...yeah I dunno. I doubt that but, you know, don't blame me if things go wrong. I'm just the messenger. Maybe keep a backup or something so you can go back to your ... steam version ... later if Microsoft decides to be weirdos and ban people for importing saves like this.
Anyway have fun playing this weird ass game for those of you that are. For those of you that aren't, I hope you enjoy it in 10 years when it's been modded to high heaven and you can actually keep a consistent 60fps on your 8060 TI