I think nebula is really cool and am heavily considering it in production.
Having a paid-for service that makes things easier is a good way to keep money going into the project, I think. And it feels a lot safer in terms of rug pull than tailscale/headscale. The android apps not being in fdroid and have some other limitations sucks… but I feel like those are easier to solve than some other issues that could be there.
If you want tailscale, but not tailscale, check out netbird. You can self host the auth server and it isn’t some side project, the whole auth server is open.