I used to work with a guy that was very visually impaired and he used a 40" monitor set to VGA resolution. He would still have to crane his head to the left & r

I used to work with a guy that was very visually impaired and he used a 40" monitor set to VGA resolution. He would still have to crane his head to the left & right sometimes to follow the mouse on screen. Going to something like a 49 or 55" television could work but you need to check the field of view at the distance they'll have it set up. Get a piece of cardboard at your largest anticipated screen dimensions, prop it up at their normal viewing distance, then put some high contrast marks on the edges & in the corners and see if they can make them out without too much head rotation. If they can't then cut the cardboard down to the next smaller TV size and try again. Once you have bought the right sized TV, then adjust the resolution so they can make out screen elements (the window close button is a good one to test against). Then adjust the mouse size, browser zoom, etc.