Comment by Fnoord

Very cool! Azeron makes these but not as hand-held (might be of interest for them?), and much more keys. Because they have so many keys, you can do some easy chording and what not, allowing you to completely replace a keyboard with one. Which is great for people who only have one arm/hand, including war veterans.

They have a 60 days return policy which I find very generous. They're based in Latvia. Some parts are 3D printed. Their website [1].

I mention them since I happen to own a Cyro, which is an outlier to their portfolio: a vertical _mouse_ with a lot of buttons. The only decent one I'm aware of, and the choice is very limited in that space. I'm happy, though I'd love to have it wireless. I tried modding it with USB2BT but ran into some issues, YMMV.

[1] https://www.azeron.eu