"Squash-Rebase-and-Merge" as an available action

We're a team that's currently using the "merge commit" setting for a repo. Changing to other "Merge request" settings is painful:

There are people who keep their MR branches up-to-date using git merge origin/master, preferring that over rebasing their branch because they don't have to re-resolve merge conflicts every time they integrate new changes from master, if an earlier integration from master did have a conflict. For example, within a feature branch, disabling some tests in one commit, then re-enabling tests in a later commit. For these people, the "Rebase" button in the Gitlab Web UI does the "wrong" thing for them.
Other people aren't very familiar with rebasing. They click the "Rebase" button in the Gitlab UI, but then they can't
Other people are really diligent about keeping their MR branches perfectly up-to-date with master by using git merge origin/master right before merging. It's burdensome on them to then also have to rebase, even when it would have
We want to use other "Merge request" settings because it helps making cherry-picking easier for maintenance release work.

When the repo setting is "Merge commit with semi-linear history" or "Fast-forward merge"

And there is only one commit in the branch

In addition to a "Rebase" button

Have a "Rebase and Merge" button, which Rebases and Merges.

When the repo setting is "Merge commit with semi-linear history" or "Fast-forward merge"

And there are multiple commits on the branch

And the MR setting is "squash commits"

In addition to a "Rebase" button

Have a "Squash, Rebase and Merge" button, which squashes, then rebases and then merges.