I’m running Navidrome on my Raspberry pi (4). On my phone (Pixel 8) I use Symfonium to connect with Navidrome. When I’m travelling I use Tailscale + Mullvad + Symfonium to play music from my rpi.

Firefox & Thunderbird Collect User Data by Default (in Violation of European Law)

Have you tried Tempo (FOSS)?

I use LawnchairRelease, a fork of one of the devs from Lawnchair. You can also use the original Lawnchair Launcher

Have you tried Harmony Music?