I can never remember the nuance between Github and Gitlab but often want to fetch and checkout a specific pull/merge request when reviewing code. Why they need to implement this feature subtly different is beyond me, but alas.
Then I can use this reference to stuff with PR e.g.
git checkout -b pr/596 upstream/pr/596
will create a local branch
git cherry-pick upstream/pr/596
is handy for single commits it will bring the patch from PR to my local integration branch
and good thing is when I push my integration up into github it knows about the PR commits and can cross reference them.