Accept auto-correct suggestion with one keystroke
I have 69 non-modifier keys on my MacBook Air and 9 modifier keys. Having worked my way through all 78 single keystrokes possible on my keyboard, I can say with confidence that none of them have the effect of both accepting the autocorrect suggestion and not producing any input on your system. If you are looking for a single key press, the answer is definitively, as set up out of the box, no this cannot be done. Once you open the door for multiple key presses, there are options, as you acknowledge, but if your standard is a single key press, no, it cannot be done.