In case you don't know this is actually how smartphone keyboards work in Japan.

This used to be a thing....

https://en.wikipedia.org/wiki/FrogPad

I'm not sure they ever made it too far but I always wanted to get one.

I bought one, so I can attest that the hardware was real (bluetooth, left-handed model). Alas, it's lost somewhere in a pile of boxes left still-not-unpacked from my last move, and they went bust some years ago -- rumours of a new low-profile version similar to the Apple chiclet keyboard have failed to materialize as hardware so far.

The thing worked, and worked surprisingly well for single-hand typing (if, for example, you had an injury to the other paw). Trouble is, it cost more than a regular QWERTY keyboard, was slower (all those chording shift-states), and wasn't ambidextrous (left-handed and right-handed models had differing layouts, IIRC).

I remember seeing those in Popular Science and being vaguely interested.