As a musician/songwriter/producer this would help me to stop using Google altogether. Currently I use their music app to upload songs I'm working on to be able to play on my other devices.
To have a Proton music player that would be able to create playlists and albums, and even update new versions of audio, would be a great deal for me. It would keep my songs private.
Also having flac compatibilty as well as mp3 would be icing upon the cake.

I support this feature. The streaming platforms like Spotify and Apple Music are providing a terrible deal to artists making music and means customers never own the music they listen to. An alternative to this is for customers to buy physical CD's and rip them, or purchase from one of the growing digital stores like Bandcamp or Subvert (Member owned collective currently in development - very cool).

Lots of people also have a collection of CD's, however these are reaching end-of-life and will start to experience disc rot.

There is however no easy way to store manage and most importantly play digital files across multiple mobile devices using open source formats.

I don't think Proton needs to get into the music selling or streaming business, there are a number of ethical companies providing high quality open-source files for download.

What would be amazing Is if I could store these files in Proton drive, easily manage their metadata and play them on a mobile app while out and about. No horrendous streaming model, no setting up my own media server, just my files when and where I want them.

Thanks!

I recommend Grayjay by FUTO. You can find it on f-droid. It's a great app for both local files on your phone, as well as a reliable ad-free player for youtube and other music sources.

Adding developement effort for that makes no sense: a better way would be to be able to listen to synchronized music with your favorite music app (expose music files) and leave only the drive part to Proton.