There are a couple of slash-commands available on GitHub which are implemented via Mattermod. They only work on PRs.
The commands are:
/cherry-pick $BRANCH_NAME, e.g.
/cherry-pick release-5.10: Opens a PR to cherry pick a change into the branch
$BRANCH_NAME. This command only works for members of the Mattermost organization.
/check-cla: Checks if the PR contributor has signed the CLA.
/autoassign: Automatically assigns reviewers to a PR.