> If so, why has it not been done?

Because of the 30 million lines problem. Writing a serious OS kernel nowadays is flat out impossible: the hardware is just too diverse, it requires too many drivers. The best we can do right now is just add to an existing kernel. Kind of a vicious cycle: the more drivers we accrete to any given OS, the more impossible it is to get feature parity from the ground up.

The only solution to that is for hardware vendor to standardise their interfaces (at the hardware level), and actually give us the fucking manual. And I mean the real manual, the one that tells us voltages and pins and baud rates and the actual wire formats required to talk to it. A proprietary Windows driver is not a manual, even if it comes with an SDK. Heck I’m not even sure the source code of a Linux driver would count.

But they won’t do it. They just won’t. So unless we do something drastic like forbidding hardware vendor to ever ship software (to force them to standardise and document their actual interfaces), writing another OS that can actually compete with the existing ones will remain flat out impossible.