There actually have been attempts frmo people to try and make touch screen keyboards, although all of the ones I've found are in HTML.
Here's one I have on hand:
https://aqwek.github.io/stenobuild/It doesn't work without a touchscreen, and it is incomplete, but it works. I remember finding another one, I'll get it for you all. This is completely possible, but it would be a hard thing to do.