I'll do that. I already see overlap with Karabiner Elements, but it does seem like everything in this space overlaps everything else, so... par for the course.
Thanks for the tip!
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.
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.
1: https://github.com/kmonad/kmonad/issues/227