First step in playing a PC game is to go into options and try to memorize the controls. This could be useful for gaming or specialized applications like CAD.
The first step is to rebind the controls because they're all wrong. Even so, I do occassionally forget what went where. So a thing like this could be useful. Of course it would never be supported unless it were common, and I don't see it becoming common.
Even with cad you tend to memorize, that and it doesn't (my exp is limited to autocad) use off hand chording too often. mostly its keying in short commands, such as 'li' or 'c', followed by an 'enter' action key (often space bar)
Perhaps it could be more useful for apps without a cli, like a DAW software package?
Nah. Displaying keyboard shortcut hints on screen next to the button at mouseover, which many applications have done for at least a decade, is much more efficient. Constantly looking down, looking up again, looking down etc. is terribly inefficient.
I think there's better use for screen estate than placing buttons on them when you already have a hundred or so buttons available at your finger tips.