ProCutX by Pixel Film Studios is free for a limited time, down from around AU$20 or so. It’s billed as a control surface for Final Cut Pro X which runs on your iPad. You run a “server” app on your Mac, connect the iPad app to it and you’re ready to go.
It’s interesting as a novelty, but it’s much less responsive than just using regular keyboard shortcuts. As an indicator of where things could go in future with more official support however, it’s interesting.