I have a mac, and I wouldn't mind a fn-lock feature, but only from a different key combo, maybe fn+capslock. The behavior of fn (media keys or function keys) is a control panel setting, so I could probably whip up something with hammerspoon. But right now I just remap most things in my IDE so they don't require function keys.

Anyway, keyboards have needed drivers since we stopped using BIOS to read them, and fancy keyboards with macros tend to need at least a userspace daemon, but yeah this kind of thing should be as much a commodity as a VGA framebuffer is, something you just shouldn't have to fuss with. Far as I know though, USB and the *HCI zoo pretty much are that, so along with the OS's own built-in support, it should support the basic functionality of any keyboard, and provide standard means for extension. I believe the main reason any company ships a 1GB keyboard "driver" these days is the bundled shovelware and spyware.