I have a folder of MP3s, some of which date back to 1999, just a few years after the format was popularised. Most of them have utterly terrible names (think RIDEONAM.MP3). I think at this point they might even survive the heat death of the universe. And they’ll still be terribly-organised.
I used MusicBrainz Picard when I stopped paying for Spotify. Went over my old library, audio tag matched all my songs, added all metadata, sorted everything. I moved it to Nextcloud and using the Music Player plugin, I have my own Spotify using any supersonic/ampache client. Life is good.
What client do you recommend on Android