To what extent is thinkpad keyboard programmable?

[replica9906]

I'm looking for an answer in general, but I'm mostly interested in X200 and T430. I'm a big fan of QMK. Will daily drive X220 as desktop replacement and switch from Mac to Linux, so I'd like to know how programmable ThinkPad keyboards are. I just feel like there are limitations since they are built-in and (?) running proprietary firmware.

[dr_st]

I think the answer is the keyboard is not programmable at all? It's just a passive matrix. The logic is in the embedded controller chip on the motherboard. That one is quite programmable, if you have reverse engineering skills, since the source code is not available.