Facebook does not come on their unlocked phones. I’ve set up my S8 and S23, as well as Note 9 and Note 22 for family and none of them came with bloatware aside from Samsung’s apps. However I got a used Galaxy tablet on AT&T and it had so much crap on it. At least it’s removable using ADB.
Plex does alright at suggesting music from your own library, and also has some really nice DJ-like song transitions that are legitimately way better than any other track fades. However, Plex users have been frustrated with the company’s slow response to fixing long-standing bugs, and some of the features are paid. It’s also not open-source.
No idea if it can suggest music that isn’t in your library; I know that they integrate with Tidal though, so maybe if you have that it’ll also suggest stuff from Tidal?
I seem to be in the minority, but I’ve never had issues with it resetting my default browser.