Doesn't the projection require one hand to be up and in a flat position, and the other hand interacts with it? Meaning it requires two hands?

Apple's implementations are for 1 hand operation. You can operate the watch's touch screen while holding a steering wheel for example.

What's the difference between the objectively not great screen that is my hand, and the oled watch that doesn't require both my hands for operation?

EDIT Heck this requires one hand just to see anything. I can look at my watch without any hands!