Matias has a neat one-handed keyboard. It's quite expensive for what it is, especially considering these days where it's so easy to get a keyboard with remappable keys. There's a simulator on the sidebar at the link, and IMO it's quite intuitive.
I tried that concept whith my ergodox when i had an arm in a splint, but i couldnt quite get my brain to wrap around it. I could type on the right key, but not press the mirror/switch key at the right moment.
What would have made it easier is if it could infer the right key like an autocorrect
https://matias.ca/halfkeyboard/