What you need to do is the following:

- Create an empty repo on GitLab.
- In your local checkout of Guix, add your GitLab repository as a Git
  remote.
- Push to your GitLab repository.
- Create a wip-jami branch and commit your changes there.
- Whenever you want to update "master", simply "git fetch --all" then
  rebase your wip-jami onto origin/master.

Let me know if you want more details.

-- 
Pierre Neidhardt
https://ambrevar.xyz/