Your Recommendations for Corded Keymappings (e.g. Techinques and/or Software)

While I'm particularly looking for chords (ex: if jkl; are all keydown at the same time then send the space keypress) I'd be happy to hear about your keymapping approach in general. E.g. how do you organize your layers, have you needed to custom compile anything, mapping choices you regret but are too hard to change now, etc.

I got my first ergomech board recently. I've got the background to flash the board manually and code everything in C. But before I go down that very deep rabbit hole, I wanted to see if what others had done/learned.

Personally I'm not planning to go full asetniop with cords. I think I just want a handful of chords to go along with layers.