Or Thumb-key, an open-source take on that.
Is it like retraining yourself to use Dvorak? Or more like learning the Palm strokes?
Took about two weeks of daily driving until it was no longer painful, then three months until I had matched Qwerty speed. So probably similar to your thumb-key experience.
I picked it up to a usable speed within two days, helped by the fact that I use a lot of technical terms that autocorrect used to dismantle, so the baseline was much worse.
Look — I don't know if it was on purpose, but I chuckled.
edit: I tried it and I already like it better.