Thumb-Key
About
Thumb-Key is a privacy-conscious smart keyboard, made specifically for your thumbs.
It features a 3x3 grid layout, as many older phones had, and uses swipes for the less common letters. Initial testing shows that you can reach ~25 words per minute after a day of use.
Instead of relying on profit-driven, privacy-offending word and sentence prediction for accuracy, as do most popular phone keyboards like Gboard and Swiftkey, Thumb-Key uses large keys with predictable positions, to prevent your eyes from hunting and pecking for letters.
As the key positions get ingrained into your muscle memory, eventually you'll be able to appromixate the fast speeds of touch-typing, your eyes never having to leave the text edit area.
This project is a follow-up to the now unmaintained (and closed-source) MessageEase Keyboard, which is its main inspiration.
view the rest of the comments
You may be interested in Stroke Input Method: it's not Thumb-Key, but it is a mobile IME for Chinese that attempts to have as few keys as possible, i.e. a key for each of the five basic stroke types that you press in sequence to type a character one stroke at a time.
I've always thought it'd be really nice if that IME could add some sort of Thumb-Key-esque flick input support, like flicking a stroke key to type one of the eight most common radicals beginning with that stroke. That way, instead of having to type ㇐㇑㇕㇐㇐㇐㇑ to get 車, I could just swipe down on the ㇐ key to type the whole 車 radical all at once. But until somebody actually programs that idea, I think Stroke Input Method is the best you'll get.