This reminds me a lot of the "Mirrorwalk" layout for the Twiddler chording keyboard: https://forum.tekgear.com/t/mirrorwalk-config-the-walking-la...

Each letter is a two-button chord, but in practice, each letter is an arpeggio because the Twiddler only sends a key event when you release a button. The layout is designed so that when writing English, there is a very high probability that the second button you press for a letter will be the first button you press for the next letter, so you can keep that button held down, press the second button, then release the first button to send the next letter. Your first three fingers (it doesn't use the pinky row) will "walk" around the three rows of the Twiddler.

This is kind of making me want to pull out my Twiddler again, I really haven't used it since I gave up on trying to run Illustrator on a Surface tablet instead of a Mac laptop.