The more I think about it, the more skeptical I am that getting notifications via the touch bar is very useful. I rarely look at the keyboard, so my chances of getting notified are smaller than desktop notifications - although maybe the motion/change would draw my eye.
I think what might be useful is context-sensitive refactor buttons for IDEs (which are often behind key combos that I forget if I don’t use them frequently). Even handier if it reminded me what the key combo was when I used the touchbar version. I might try to whip this up during my tool sharpening this week.