It's already too late to edit my previous post, so I just wanted to give an update.
With Apple Vision Pro's accessibility features, you don't need any other input other than your eyes. So your friend's mom can indeed use Vision Pro using AssistiveTouch and Dwell Control to create an 100% hands-free experience.
How to Use AssistiveTouch
With Apple's accessibility technology AssistiveTouch on Apple Vision Pro, an always-accessible menu appears. It lets a user perform actions such as opening Control Center, Notification Center, and the Home View. With Dwell Control on, you can go 100% hands free by giving you options such as tap, scroll, long press, and drag. To enter any one of these modes, simply perform an extended gaze at the Assistive touch menu, and select the mode you need. When you are in this mode, a user can perform an extended gaze to use any one of these actions. For instance, on a webpage, a user can click on a link in by gazing at it in tap mode and continue reading an article in by switching to scroll mode and long gazing at the area to scroll in. You can even drag and drop an image by performing an extended gaze at an image in long press mode, switching to drag mode, extended gaze at the selected image, move your eyes to the desired final position, and performing an extended gaze at the image again.
I hope you understand how to use AssistiveTouch on Apple Vision Pro now! Tell your friend's mom about it. The price is worth it.