I don't have the links handy now to make an effortpost, but there seem to be more than a handful of open source (and not only?) projects for such keyboards. Not

I don't have the links handy now to make an effortpost, but there seem to be more than a handful of open source (and not only?) projects for such keyboards. Not all with 8 keys, but chording and one hand is the focus. You can work with something like this with a numpad, there are a few QMK numpads out there now, I believe the cheapest is ~50-60$. Now, for one-handed keyboards: they are all super expensive, but intriguing stuff, for sure. Of the top of my head: Mattias half-keyboard, Tipy, the good old Maltron, some odd keyboard in a normal format, but with a circular layout that I don't remember the name of, and Frogpad (or something) that seems to have a dodgy fame, if it is still being sold at all. I believe these are all the commercial ones. On custom keyboards, again, some split keyboards have a controller on both halves of the keyboard, so you can use them standalone. You can go to town and make your own layout there. Although I am doing some research on that these days(-ish), I have no links handy because I am not interested in chording, and the commercial ones are expensive. And I am sloppy, and I remember some stuff... Edit: QMK has some "one-handed mode" thingy nowadays, I have not looked into it at all.