but waiting 5 seconds for a keystroke to be echoed (sometimes) is appalling. you would not get permission to do a user study from an irb. it would be denied on grounds of needless cruelty to experimental subjects
it would fit the use case perfectly if you had a low-power microcontroller that updated the screen in response to keystrokes, but what you're describing is a user interface design botched for no good reason
even the rp2040 would work for that at the weekend level
this is not quite a 'solar freakin' roadways' level of mistake because you could fix it with relatively minor tweaks to the design, but if you don't, you'll be left with a design that's unusable on battery, either because of battery life or responsiveness
fwiw i don't think restarting a computer in response to a keystroke is an elaborate workaround at all; that part of the design is perfectly reasonable
check out how mosh predicts keystroke effects for 'speculative local echo' and think about how you could do that on the rp2040 (or ideally an esp32 or apollo3 or something) while you're waiting on the giant linux behemoth to awaken from its slumber and restart gomuks or vim or whatever