Yup, someone already made a PR for to add these! It turns out the behavior is pretty subtle in terms of how it handles count arguments (it's actually stateful!), and where the focus moves. I'll take some time to figure out how to exactly match the vim/less behavior, but that should be coming soon!

I'm more of a ctrl-e/ctrl-y guy myself, so I didn't feel a need to implement these commands right away.