For me, calling something an OS requires it to have it's own kernel ... maybe thats just me, but I think this is the 2nd project this month which has called itself an OS when in reality it is just a GUI.
It already has a kernel, except it uses the host OS's system calls instead of its own drivers. Once you have a runnable OS that runs as a separate Unix process in its own address space, it is actually possible to port it over to bare metal by providing all the modules that the OS would normally provide: memory management, graphics, device management and HAL, keyboard/mouse input.
See https://github.com/froggey/Mezzano for something that can run on bare metal.