Why hasn't anyone build an AI Keyboard on iOS?
You mean a keyboard that predicts what you want to type before you type it?
What's an AI keyboard?
I had the same question. Apparently, it's an autocorrecting keyboard on steroids: https://www.clevertype.co/post/what-is-an-ai-typing-keyboard...
(That link is to an explainer for an AI keyboard product. I'm not endorsing that product, I know nothing about it, but the explainer seemed very good.)
Raycast attempted it, but imo it's a bad job.