That's not really true. It has all of the primitives you need to support PCI graphics devices (or even memory-scraping legacy VGA if you hate yourself). It had

That's not really true. It has all of the primitives you need to support PCI graphics devices (or even memory-scraping legacy VGA if you hate yourself). It had all of the primitives you need to do emulated USB on 10.10 -- passthrough is a different matter. For implementing GOP you need to support UEFI, generally, but beyond that it's just supporting another UEFI protocol.