Sublime Music is a GTK app for connecting to personal-music-server instances - https://sublimemusic.app/
(Specifically, for servers that run the “subsonic” API, which there are a few of to choose from. I’ve been using Navidrome to great success on that front; it has a fine enough web front end as well as multiple mobile clients to choose from. But a true desktop app would be far superior … especially when you want to log out of everything for a while.)
Anyway, the base package for Sublime Music is somewhere in the Debian experimental-to-testing pipeline, but not available in Ubuntu repos yet AFAICT. More importantly, the developer has included a handful of odd packaging options but nothing mainstream (closest might be that it’s apparently possible to do a flatpak of it, but it’s not actually functioning in the Flatpak-project hub, so even that requires extra steps for users…)
It’s Python+GTK, which is a good starting position. Source is hosted at GitLab.
Fair warning, the developer seems (from what I can tell) to harbor some hostility toward Ubuntu, so that may become a problem (see, for example, that they opened an issue for snap support and commented themself that they weren’t willing to work on it: https://gitlab.com/sublime-music/sublime-music/-/issues/48 )
Anyway, I think it would be a good addition, and possible not an arduous one. Might even be nice to demonstrate that considering the snap ecosystem is not difficult…