Thumb-Key app
Thumb-Key is Internet tool that is open source under the AGPL-3.0-only license. Thumb-Key is a privacy-conscious smart keyboard, made specifically for your thumbs.It features a 3x3 grid layout, and uses swipes for the less common letters. Its easy to learn, and designed for fast typing speeds.
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.