An excerpt from their writeup:

There are a whole lot of different keyboard solutions on Android, and let’s be honest: a lot of the offerings aren’t great. While many of them have strengths, I initially struggled in my de-googling of my life to find a keyboard that had everything I wanted with regards to layout, swipe typing, and voice input. What follows is the best method I’ve been able to come up with (credit to the cowboy-hatted individual who clued in me into FUTO voice).