Plex's specialty audio client Plexamp is pretty good if you want to make your own "radio stations." And if you have a Plex Pass, the server does "sonic analysis" of each track so it can do a good job of playing related music in its smart playlists.

Of course, Plex Pass ain't free, but if you are in it for the long haul the lifetime purchase may be worth it.

(Everyone's worried about Plex's future right now but I would be surprised if they killed self-hosting. That's another topic though.)

There’s a federated platform called Funkwhale that’s very similar to that.

https://www.funkwhale.audio/

I think last.fm might still exist. I just used it for the 'scrobbling' — stats way before Spotify Wrapped was a thing