> How do you get everyone to run the tunneler on all the machines that they could use?
There's apps in the stores for Android/iOS/MacOS and installers for Windows. It's basically equivalent to running any other "VPN type of client". Wireguard does the same thing (in fact for Windows we used Wintun from Wireguard which was awesome). OpenVPN/Cisco/ZeroTier etc.
OpenZiti is also working on an "install-less" option for users that can't (or don't want to) install apps on their own. It's not ready/rolled out but hopefully it will be soon.
The tunneling apps provide some pretty cool functionality though, most notable is private, authenticated DNS. IF you were running the tunneller you could go to "jenkins.ziti" or whatever made up DNS name you like.
If you can't install a vpn client like that then yah, it'd be a non-starter for accessing jenkins like this.