It should be an app like Spotify Not including combinations like: Newpipe + VLC because I want recommendations on what I should try within the app, and offline downloading. I like the idea of using a front-end for the other service if no Foss option exists. Any opinions?
The best would be to just torrent music on-demand, then use any music player app you like.
If you want a large library, you could run a music server like navidrome, then get the app DSub to connect to it.