As a status update on this topic, SonixQMK now has support for most K* RGB boards ( excluding the K1 and K10, someone would have to give us a hand there with their wiring) and recently added a bunch of White boards, as well as the C* lineup. Optical switches support is in and ...
Both the Keychron K1 and K3 boards have the option for red, blue, and brown low-profile mechanical switches, with the former supporting Gateron mechanical switches and the latter both Gateron and Keychron low-profile switches. The Keychron K7, however, on top of offering those six switches, ...