For someone who want to setup a private network between host/devices, I feel the dilemma is always:
1. Trust a third party like Tailscale by giving them the key to your kingdom, but everything is incredibly easy and secure.
2. Self-host but need at least one host with a fixed IP address and an open port on the Internet. What requires a set of security skills and constant monitoring. That includes headscale, selhosted netbird, zerotier or a private yggdrasil mesh.
When I look at these zero trust solutions need 80/443 for what seems some type of bootstrapping
Better it happens using the same approach wireguard takes (udp/stateless). Though I'm not sure if there's more than just bootstrap taking place, maybe constant routing updates etc
You can conceal that open port with some form of port knocking. Though this does reinforce your "easy" point.
Also, if it's an UDP port, then using a protocol that expects first client packet to be pre-authenticated and not emitting any response otherwise gets you pretty damn close to having this port closed.