How would the plausible deniability piece work? If you stream some bytes to someone else, you can't deny doing it. Unless you imagine this working over Tor, idk what the performance of Tor is these days but I never thought it could support such an application.
Music is relatively small. Tor is totally capable of hosting zlibrary without bandwidth restrictions getting in the way.
By plausible deniability I simply meant adopting a similar approach that Stremio has, to keep it on the good side of App Store approval processes. The app itself only allows for creative commons content by default, but with the right incantations it can host anything.