But it's not necessarily a caps lock key, but an extra function key more easily accessible. There's quite a few keyboard designs out there that have button clusters for thumbs, so that you can use your thumbs for more than just pressing space.

In the same vein: I discovered the pleasure of the major modifier being under the thumb on MacOS, triply astounding on the MS Natural 4000 keyboard with its huge alt keys (they map to ‘command’ on Mac due to the position). And then I learned that Emacs was made for keyboards where the ‘control’ keys are under the thumbs.

I have an Ergodox EZ keyboard (which is programmable using QMK, or Oryx which is a wrapper around QMK) and I set caps lock to esc on tap but ctrl on hold.

QMK supports as much as 4 different behaviors per key: - tap - hold - tap-hold - double tap

And you can also set keys to change the layer each with their own behavior for caps lock.

fascinating!

i always wondered why soft-BOL is set to such a difficult key to press (^) when it's such a useful movement.