Yes, having a special keyboard can be limiting in that it’s a pain to cart around to hook up to laptops, etc. and to get an extra in case it fails.
It still could be nice to have something optimized, though. If you ever design one, please share it, because I think you’d get more interest than you’d think.
I began to have interest in developing for everyone (primarily for differences for vision, though difference in hearing, memory, learning also) about 13 years ago, and got little support from the small company I worked for. We had a very color-specific interface, because we were space-limited. Then, wouldn’t you know it, our next manager was red-green colorblind, but it didn’t bother her.
I got jaded about it, learning that basically no one cared enough, and that people just get ignored and struggle with their adaptive devices. This still pisses me off, and I was once thinking heavily about applying a job where I could do something about it, but I don’t have the required background.
With AI, there’s beginning to be almost no excuse for someone not to add first-class support for all types of people into their interfaces and process, but people still continue to design like everyone is a twenty-something y.o. with full hearing, 20/15 full color vision, 130 IQ average, and no memory or learning differences or other modalities.