Nowadays I question the necessity of vpn overlay networks. Why not just serve QUIC/HTTP3/Iroh over the internet directly in your application? And use oidc/client cert for authn/authz
Those days, rather that actual "vpn overlay", I use Tailscale myself mostly for the Tailscale Funnel - a somewhat stable, yet free arbitrary DNS and free reverse proxy termination of incoming data for anonymous users.
Postgres also has TLS + oauth2 support
> rather that actual "vpn overlay", I use Tailscale myself
I actually already had tailscale in mind when talking about "vpn overlays" :D