I know there are different use cases for each, but generally do people prefer self hosted nextcloud, proton docs, or libre office?

I use the former. How does it compare to the other two?

Are they on Deezer? If so, look into deemix-gui.

I’m not too familiar with roon. As for proper metadata, I’ve not had any problems with MusicBrainz’s metadata grabber. It’s a built-in plugin that comes with Jellyfin. Deemix uses your deezer account, which I believe requires the paid version if you want lossless flac files, and I have it configured to place the files in my Media share, which Jellyfin reads from. Symfonium is the android client I use that works with selfhosted media servers.

Deezer (paid for flac - lossless files) + Deemix-gui + Jellyfin + Symfonium works quite well. Though you need to have a media server, so not exactly a drop-in replacement.

I don’t own P3 Reloaded, but is this sort of like the additional content that usually comes in Persona 4 Golden and Persona 5 Royal? Shouldn’t this have been included in the P3 Reloaded release?