Earlier quoted context omitted.
Wireguard can do what you're describing.
Wireguard can't punch through NATs or firewalls without third party software like Tailscale. Also I'm pretty sure each peer to peer connection needs to be individually set up in a config file ahead of time
It's not as simple to make it reliable as it is with Tailscale, but it works
It doesn't universally work without a helper script and a STUN server, though - you need a suitably "friendly" NAT that has reasonably predictable behaviour with respect to port mapping and/or just one side of each pair behind a NAT.