The Subsonic API has a similar "jukebox mode" feature which some servers support, that plays music on the server's audio device instead of streaming it to the client app. So you run your server on a device connected to your audio system, and if you have people over anyone can queue up tracks. Gonic supports it, and Navidrome will once the next release comes out (or if you build it from source). I'm not sure which Subsonic clients have a UI for the jukebox mode though.

For something completely different, mpd was basically designed for this. But it's a completely different API and completely different set of clients, and streaming to a client is not really something mpd does. Of course you can always run an mpd server and Subsonic-compatible server side by side pointed at the same library.

Not quite as self hosted as other things here but, You could look into plex. They have made Plexamp free to use now and it is actually pretty good. Has some good features. And more importantly has a phone app that works.