One fork with multiple branches suffices. You can also do a --depth 1 clone to skip the history (though it’s of course still a bit of a heavy repo).
We’re aware that the package submission process is not the simplest and we want to have a more direct way in the future. But that would require a whole lot of engineering which we can’t prioritize at the moment. Using GitHub as an stopgap solution gives us a lot of things for free (e.g. review tooling).