Music assistant is getting baked into home assistant, and can provide a control plane: https://www.music-assistant.io/

You can use squeeze lite to make servers it clients: https://github.com/ralph-irving/squeezelite

You can install it on an esp32: https://github.com/sle118/squeezelite-esp32

And there's a decent wiki full of stuff about it: https://wiki.lyrion.org/index.php/Main_Page.html