rauthy looks interesting. I might even write a nixos module so I can try it out.
As an aside, despite the learning curve, i think nix is a really good fit for community hosting. Everything is way less brittle and you can almost always roll back to a working config if something goes wrong in an update.
I know it doesn't use standard sysadmin tools, but building atomic deployments with standard tools is way more complicated, I think, than learning nix.
I'm not a system administrator and as I've tried to host stuff on my laptops, and such nix has been the thing that has taken the stress out of maintaining my own stuff.