[Findecanor]

There is Edgar Matias's "Half Keyboard" layout, where the right hand's keys of a regular keyboard are mirrored on the left hand when holding a modifier key with your thumb. The idea is that if you have learned touch-typing then muscle memory for the right hand should be available also on the left.

Matias wrote an article [1] about it and then made it into a commercial product [2], but the concept should be possible on any programmable keyboard. Perhaps it would be possible with a AutoHotkey (MS-Windows) or Karabiner (MacOS) script otherwise.

There is a large scene for more-or-less DIY "ergonomic" mechanical programmable keyboards with various different physical layouts, but common themes are 1) that they are split in a pair of two physical keyboards and 2) that they have multiple thumb-keys for modifiers / Return / Space. You could build and program just one half of such a pair. Many years ago I programmed an ErgoDox with the HalfKeyboard layout, just to try it out, and that ErgoDox I had built on a budget from mostly salvaged vintage components.

[1]: https://www.semanticscholar.org/paper/One-Handed-Touch-Typin...

[2]:https://matias.ca/halfkeyboard/

[gidgid09]

I severely broke my wrist some years ago, which prevented me from using my dominant hand for many weeks. During this time, I used an AuthoHotKey script based on the Matias documentation in order to allow myself to continue to work efficiently in my technical role. The script worked by "mirroring" the layout of the left side of the keyboard with the right during the time when the spacebar was continuously held down. A momentary press of the spacebar still produced a space character.

I can wholeheartedly endorse this method. I never measured it precisely, but I would say I was still upwards of 80% proficient in typing speed using this script with just one hand.

[TurkishPoptart]

Looks cool, but not sure why it's $600...