Im not sure how difficult it is to setup a Tailscale client, honestly.

The Zerotier setup is just installing and joining a network by an id. The Windows version has a bit of a GUI, where you have to right-click on a status bar icon, click Join network, paste in the id and join. The Linux version of the client has a cli, which is imho even better, as you can just send them a whole command to copy into the terminal.

I admin a Zerotier network for a bunch of kids that wanna play Minecraft, and they havent had many problems setting up.

There is a bunch of information on self-hosting the whole system, but Ive honestly never tried any of that. It was just nice that this was “just the open-source LogMeIn Hamachi with a superior implementation of everything”.