I just stumbled on a self hosted project similar to tailscale: https://github.com/gravitl/netmaker. There is also https://github.com/juanfont/headscale which is an open sourced implementation of the Tailscale coordination server. Tailscale "just works" and makes things incredibly easy for personal use, but it's awesome that there are also similar self-hosted options out there
(Repo owner here) I'm planning to build my own router with OpenWRT and install Wireguard on it, however due to the chip shortage I can't get the hardware for a reasonable price yet. Netmaker looks amazing, I need to play with it.
ZeroTier is certainly another viable alternative, but their self hosted option still relies on the ZeroTier root servers (you can self-host roots, but they don't support removing theirs [1]), and their licensing for the self hosted product is more restrictive than something like netmaker.