I think that the biggest thing missing is an open/libre mrc.bin implementation that is written from scratch (as a clean room implementation). Coreboot to this

I think that the biggest thing missing is an open/libre mrc.bin implementation that is written from scratch (as a clean room implementation). Coreboot to this date still relies on the Google Chromebook's dump from more than a decade ago. And it's probably the hardest reverse engineering challenge, because Intel isn't offering any details.