I don't yet know if it's any good, but I'm looking into Funkwhale right now, which was originally created as an open source alternative to Grooveshark. It is, however, explicitly designed for music under free licenses (whether creative commons or something else), so it's not an option for many artists.

Another option I just came across is https://codeberg.org/simonrepp/faircamp which sets out to be an open source Bandcamp clone, conveniently enough. It does appear to have payment options, but I'm unsure whether they're actually functional since I haven't tried it myself yet (but I plan to).