QMK worked well for me, using supported controllers but entirely custom odd-ball hardware designs. It handles the somewhat annoying bits (USB protocols etc.) wh

QMK worked well for me, using supported controllers but entirely custom odd-ball hardware designs. It handles the somewhat annoying bits (USB protocols etc.) while allowing you to completely rip out most of the built-in logic (matrix code, scanning, layers, ...) without touching the tree. It also has a lot of kitchen sink functionality, although some really weird omissions as well (the only way built into QMK to receive free-form communication from the host is through virtual serial port). Overall it's kinda neat for that specific niche. But as a "framework for [basic] customizable keyboards" it is imho a poor choice because of those omissions and what you mention.