Admittedly, I haven't gotten around to actually using WireGuard yet, but I think it's pretty much as simple as Linuskendall said. https://www.wireguard.com/quickstart/#nat-and-firewall-trave...

Also see this guide on using a public VPS with a Wireguard server to share resources behind two different NAT'd networks: https://staaldraad.github.io/2017/04/17/nat-to-nat-with-wire...