There is no command git issue create [hostname] [title] [description] and if there was such a command, it'd require authentication on the specific instance to prevent spam.
You still need to create an account on each Forgejo instance to report a bug there...
And even, if you commit code or make a pull request... Git might be decentralized (you can develop with your friend independently from each other and merge it), but try to commit code to a GitHub project, GitLab instance or Forgejo instance without having an account there to authenticate yourself... It won't work.