That last sentence is a bit nonsensical. Apples and oranges. Coreboot is not a standardized interface for OS boot loaders, Coreboot is only low-level early init

That last sentence is a bit nonsensical. Apples and oranges. Coreboot is not a standardized interface for OS boot loaders, Coreboot is only low-level early initialization code. Coreboot loads a payload… like EDK2.