It's also possible to compile it on its own using `gcc -c -x c -D RGFW_IMPLEMENTATION RGFW.h`
Nuklear is not a true single-header style library, it only uses that as a format. The difference is that the design is far less compact and lightweight than a stb-style library.
I'm pretty sure GLFW has some files that are nearly the same size as RGFW, for example.