I run a forgejo server on the internet for myself so here’s my two cents.
OpenID or any other log in method is just a way to log in to an account on the forgejo server. With registrations disabled it shouldn’t be able to create an account, so there should be no issue. All the extra auth methods also need to be configured and are disabled by default.
Bot traffic can be pretty horrendous once they find your server, I’d say Anubis is basically a requirement at this point. I would also strongly recommend setting up fail2ban for http and ssh, and disabling ssh password auth.

















People are mad at me for helping to build the torment nexus :(
But at least that means people are being tormented by the torment nexus :)