Discussion
Ok, TIL.

But I don't know how to apply this ... with these refs available do I have to configure them as in the screenshot or can I use them meaningfully without an extra config, too?
$ git fetch
$ git ls-remote | grep merge-requests/604
From git@gitlab.com:walletscrutiny/walletScrutinyCom.git
80139aed030bb303682865d74cf4204c41b760fe refs/merge-requests/604/head
70affc2f1b0a2cb73a35992d5357d272704fe5c8 refs/merge-requests/604/merge
$ git checkout origin/merge-requests/604
error: pathspec 'origin/merge-requests/604' did not match any file(s) known to git
So I can $ git checkout 80139aed030bb303682865d74cf4204c41b760fe
HEAD is now at 80139aed03 Third batch of _desktop wallet reviews and images
but as gitlab allows me to push to the respective branch, I'd really like to have a branch and not just a revision. So I #askNostr?
git fetch origin pull/8/head:8-custom-branch-name
Interesting.
$ git fetch origin merge-requests/604/head:tmpMR604
From gitlab.com:walletscrutiny/walletScrutinyCom
* [new ref] refs/merge-requests/604/head -> tmpMR604
$ git checkout tmpMR604
Switched to branch 'tmpMR604'
This will be handy. Thanks!