Look into sanctum [1] it's cathedral mode. You can self-host those entirely and they're only discovery nodes. Once the tunnel is up the cathedral isn't involved unless for black key distribution or if your peers are behind restrictive NAT.

There's reliquary [2] which I host and run for me and my hacker friends based on sanctum.

[1] https://github.com/jorisvink/sanctum

[2] https://reliquary.se