Thanks to the original work in https://github.com/Erlendms/karabiner-actions, I had an incredible starting place to implement home row mods on a built-in keyboard (and replace buggy HRM in QMK).
I plan to add additional functionality, but as a first-pass, this fork implements the GACS variant of HRM and is configurable to any order.
Quick Start
# Install Node (brew, asdf, mise, nvm, etc.)
mise install
# Install dependencies
npm install
# Apply changes from config
npm run build