> Plex scrobbles to Last.fm from the server, auto-populates artist metadata, does a stellar job matching similar artists and building playlists from your own collection....The metadata is defined the way I've elected to define it and it's available via an rclone mount to Google Drive.

This is so strange to me. If I were going through the trouble of streaming my own files, the last thing I'd want is to have records of every file I played and when sent a bunch of third parties who will eagerly collect that data. Self-hosting should mean getting your data out of other people's hands because what you listen to, when, and how often, is none of their business.