Horizon Worlds Desktop Editor: Camera UI Focus lock for 2D games

Okay, so I've seen some games do this (Like Goblin Wrangler), but I'm really struggling to figure it out on my own. I want to build some 2d games that would lock to a portion of the screen for VR (like a focus UI would) and I could build a nice environment around it.

But also would like to find a way to build a focused ui that the game launches into for mobile as well. I've scoured the net for docs on how to do this, but nothing's come up. Somehow a few folks have figured it out, but I'm hoping someone can lend a hand!