I programmed the image capture button on mx keys to do the shortcut of "open image capture options."
This shortcut works when I hit the comd-shft 5 buttons on my keyboard and mx keys. it does not work when I hit image capture, even though it is programmed to do so.
image capture options just give me photos of my desktop over and over, even though i have things on the screen I want to capture.

So, there seems to be no good option for an image capture shortcut.