Tailscale/headscale/wire guard is different from a normal vpn setup.

VPN: you tunnel into a remote network and all your connections flow through as if you’re on that remote network.

Tailscale: your devices each run the daemon and basically create a separate, encrypted, dedicated overlay network between them no matter where they are or what network they are on. You can make an exit node where network traffic can exit the overlay network to the local network for a specific cidr, but without that, you’re only devices on the network are the devices connected to the overlay. I can setup a set of severs to be on the Tailscale overlay and only on that network, and it will only serve data with the devices also on the overlay network, and they can be distributed anywhere without any crazy router configuration or port forwarding or NAT or whatever.