yes but why would you?

Mainly because you’re required to use their distribution, or to build on Debian, which is not to everyone’s liking.

Of course that’s an argument against proxmox, and not virt-manager and the like.

Primary goal: Navidrome as server combined with a VPN (tailscale is probably the easiest to setup but not technically self-hosted). Clients can be any that support the subsonic protocol. I personally use dsub2000 (android) + supersonic (Linux) but there are others. I’d start by testing it on your LAN to see if it’s workable.

Secondary goal: if you can get all 12 people to install Tailscale on all relevant devices then you can continue to use that. If not, you’ll need to host navidrome (or an alternative) publically preferably with a reverse proxy for better security. You could alternatively try Tailscale funnel or some cloudflare solution to host navidrome.

There’s also endurain but it doesn’t support gadget bridge integration yet (gadgetbridge needs to solve it on their end).

You sound like you want something more like navidrome which is closer to a private Spotify whereas Funkwhale is closer to a public social platform like Lemmy or Mastodon where you share music and follow others (or a little like a free bandcamp).

You still need to solve the public access problem either way, however, as others have talked about.

It was forked to veracrypt from memory. And LUKS was already widely available on Linux as alternative.

Some subsonic clients also support Jellyfin servers, so that could be a useful addition here (although I’m happy with Navidrome myself).