Exactly this. Even though I don't use git-bug anymore, I'm still a sponsor. I desperately want an issue-tracker-in-.git to become a standard.
Issues and CI are the only lock-in. The latter is legitimate because you're using someone else's CPU, but every developer has the tooling to "git diff" and write comments if we could just agree on a format.
I have trouble wrapping my head around how to make it so the public can create an issue in your git repo.
They can clone the repo, make changes, and then push. On the server, you can have a hook that checks if the commit only contains appropriate issue changes, and apply just those.
Sure, a little more complicated than “Create Issue”, but not that much for devs. We could even simplify the workflow with e.g. git-issue or something like that, similar to e.g. git-send-email.