You can probably make that happen with the QMK firmware: make the whole thing stop two hours after being plugged in. Or have a key sequence to restart the timer. (so that you don't have to unplug and plug it all the time)

That'd be an interesting feature honestly.

The keyboard in the submitted post comes with a buzzer built-in. I think they had one in the Planck that beeped when it turned on or connected to bluetooth or something. So you could program QMK to do this almost certainly! :)

And also negate your ability to by-pass it since oops your keyboard doesn't work any more.

Why not both? :-)

https://www.workwhilewalking.com/do-treadmill-desks-actually...

Hook up a cattleprod on a timer?

Or, maybe better, glue on a stopwatch.