I just use Plex hosted on a Raspberry Pi, and Plex Amp. I download mp3s from Bandcamp/wherever, and use beets [0] to auto-tag.
EDIT: FWIW, I don't recommend most people host their own music. Spotify/YouTube music is easy to use and has most music people want to listen to. I only self-host because I'm the type of person who has built a collection of mp3s since 2005, and the few times I tried switching to Spotify, I would commonly not be able to find specific things I wanted to listen to.
I self-host digital media (and have physical copies of the very best stuff) because I want to be able to access the things I like even if there's some legal bullshit about the content.
And when it's on my NAS and backed up, I can be pretty sure that I can still access it in 10 or 20 years.
Some services like youtube music also allow you to upload your own tracks and mix them in the playlist so you can have the versions of songs you want or ones that they don’t have.
Ah interesting, I remember this being a feature of Google Play Music 10 years ago as well. Nice to see they kept it around.