Kinesis has a new line coming out later this year, the Advantage 360: https://kinesis-ergo.com/keyboards/advantage360/

Fully split with the key wells, and a Kinesis board to boot.

Dactyl/Dactyl Manuform is concave. Even more, its shape is programmatically generated, so you can separate control curvature for each axis, stagger, etc. It is literally infinitely customizable.