Skip to original Dactyl and look at the configurability/customizability of the Dactyl Manuforms.
Personally, after using the Kinesis Advantage for many years, I'm going a different direction... fewer keys, lower profile, etc. E.g., Corne, Kyria, Ferris.
There are DIY mods that people have done to be able to run e.q., QMK as well as make them bluetooth.
My impression is that people who really want the concave keywells are building variations of the Dactyl Manuform.