There were electric typewriters that would repeat if you pressed a key beyond its normal bottom.

The UX trend of mapping all functionality of small devices into a single weird morse code hybrid button is pretty much this, but yeah, it's horrifying.

I have caps remapped to crtl on press and esc on release, space mapped to alt on press and space on release and the two shift keys mapped to parens on release and shifts on press.

It's quite common to do at least of one of these if you're using vim or emacs on linux.

"slam any key to continue"

Wait until they add capacitance touch and "taptic engine" to keycaps. You could register different inputs to brushing a key different ways, or add mouse movement to g and h like those ThinkPad TrackPoints. Never going to have to leave the home row again.

for some reason i imagined this applying some force feedback back to your fingers halfway back up the keypress

like if you made a typo, and the keyswitch pulsed the electromagnet to tap your finger on its way up

Of course the real application is analog. Imagine being able to control movement speed in a game with keypress depth.

Or, for the CAD adults in the room, a proper 6DOF tool without needing an additional clunky piece of hardware.