Behind the scenes of iOS and Mac Security

Apple (at least their security org) has done this before with their talks at Blackhat [1] where they've detailed pieces of their boot chain and interesting challenges they solved while building Find My's offline location feature [1]: ▶ this video

I'm curious if Apple's work on hardening their secure boot process on x86 affects this at all? For this unaware, this [0] video covers it over about seven minutes. Basically they claim to be enabling the IOMMU with a basic deny everything policy so that when the changeover to executing from RAM occurs and PCIe devices are brought up the IOMMU is able to deny possible malicious access to the firmware image. It sounds from the end of the article that there are separate DMA/IOMMU processes for the CSME, but I'm not familiar enough with stuff this far down to know for certain. ▶ this video

Apple has been moving their defenses earlier and earlier in the boot process. According to this talk[0] they are even able to foil malicious option ROM[1] and other early boot attacks. I don’t recall if they mention boot passwords specifically, but they claim to lead the industry in this regard. [0] ▶ this video [1] link

Behind the scenes of iOS and Mac Security: ▶ this video Good talk behind the reason for the T2 chip and some other Apple security stuff