You can lock down a wireguard vpn server pretty hard, because wireguard itself is essentially invisible unless you know it's there. It doesn't respond to anything but well formed, correctly signed (in the case of connection initiation) or encrypted (for the actual network itself) packets. So conceivably, you can have your vpn server not respond to public icmp, not expose even ssh without wireguard under it, and be essentially invisible to the internet.