Thank you! I think convex keycaps are very nice to have - even if just for the thumb cluster.

Thank you!

As far as options for replicating the layout go, I think ErgoArrows would be the closest - you can get it as a kit.

If it’s more about the middle keys than the a bunch extra keys on the bottom, there are many keyboards like that - Ergodox/derivatives, Kinesis Advantage360, Moonlander, Redox, Dygma Defy, and Keyboardio Model 100 all have 2-3 keys in the middle and can be bought pre-built. ErgoDash, Ergo68, and Pinky4 can be bought as a kit.

“Key spacing” is usually the term.

I think Dao Choc BLE, city42, or the various Hillside keyboards would be the closest that you can get pre-built.