I've setup an Opengist server at https://gist.thisisjoes.site. Users can login with an account on my Gitea instance. If you don't have an account, you can login with GitHub or GitLab if you prefer.
It may be Joe's site, but everyone is welcome! A general instance with an emphasis on maintaining an open Fediverse and common sense community moderation. Rules are simple and aim not to be too restrictive.