I had literally just set this up on my truenas instance yesterday (even though I’ve been using ZeroTier for some time). The key thing to recognize is that truenas whipes out any modifications to its system after a reboot, hence the need for this script.

https://alan.norbauer.com/articles/zerotier-on-truenas

I’ve heard great things about tailscale, but just have had an opportunity to try it.

Gogs and Gitea are git alternatives that offers GitLab features with less system resource demands.

Though, it would be good to understand your use case, whereby a GitHub private repository would not be suitable…