It sure can be used as a display for a Mac. Just stand in front of a Mac, and the screen will go dark and the windows will be moved to your Vision Pro.
I'm wondering if a similar trick will be used with iPhones and Apple Watches that are within view. Will they bother with the camera reading the screen and then rendering to the visor, or will they just seamlessly talk to the phone and watch to get the screen imagery. I'm assuming that would improve the quality.
Here's the point in the Keynote showing it: https://www.youtube.com/live/GYkq9Rgoj8E?feature=share&t=552...