Agreed completely on this. I almost wonder if it’d be more palatable to add a grade above A, like a Japanese style “S”.

That already exists, it's called an A+.

American high schools are already doing a form of this, with certain classes earning more than a 4.0 score in GPA calculations. 5.0 is quite common now, with 6.0 and even 7.0 scores on individual classes being possible.