As far as I can tell, all this does is generate some text that you can email to someone. It doesn't offer the ability to iterate on code reviews or track line comments, so you'd have to manage all that either via email or via a separate system.

It really depends on how you define the term pull request/merge request/request pull. The end action is to merge the code in the set of commits into a local branch, which is what all three allow you to do.

The ability to discuss code changes, etc, is separate from that. In my opinion, the terms pull request and merge requests are not entirely accurate. For services like Gitlab and Github, it's essentially asking the maintainer to review your code, so it really ought to be called review or change request.