[comfypotato]

Basically kmonad allows your home row to be modifiers on hold, and Karabiner allows combos [1]. These are both functionalities that are readily available with QMK. Ultimately QMK can do anything you can think of with a little bit of effort. If you aren't set on sticking with the built-in keyboard, the mech keyboard rabbit hole is really wonderful.

1: https://github.com/kmonad/kmonad/issues/227

[Jailbird]

Interesting - I do still want to stick with off the shelf. I have a WASD V3 (so no QMK there afiact) but also a MacBookPro - for which I'd happilly buy an [off the shelf] external keyboard to get QMK/ZMK, or really - layers/combos/more-keys-as-macros/etc. Since I'm thinking external, that's why I was looking for off the shelf options where it does seem the firmware is all-powerful.