I’d love to have the ability to still see rules & guides when I hide the UI (Command+). I often inspect designs with the Figma UI out of the way. IDK why this is not possible (maybe use a Shift+Command+R to toggle the rules & guides while hiding the UI?).
Other improvements would be to provide some keyboard override to not snap guides to elements (as in Photoshop). I know I can select the guide and use the arrow keys to move them 1 pixel at a time but moving and dragging (while not snapping) would be much faster.