I'm also a navidrome user and I run it via docker exposed via traefik so I can access my music anywhere. I can use any subsonic client on android or iOS and I can bluetooth that to my car or headphones or whatever and I can load it up on my laptop anywhere.

As you've said you just want a local application just wanted to mention that in case that's actually something that might also be useful for you.

Totally understandable. I recently thought of developing a cross platform player in C# and AvaloniaUI, but cross platform audio is not as easy as it seems, especially trying to use open source libs only and minimizing dependencies.