@cory the idea sounds similar to what I’ve done a while ago with #Platypush + #mopidy (and optionally Tidal). My implementation also uses the scrobbled tracks over a certain period and Last.fm’s API to automatically generate a “discover weekly” playlist.
I haven’t toyed with Plex in a while, but why did you have to run everything on Firebase/Supabase? If you have your Plex server running locally isn’t it more convenient to go for a fully local solution?