@sleepyowl Intel is extending BootGuard with FSP signing too (which is a blob doing all memory/silicon init magic behind the scenes) which was specifically requested by delusional vendors like AMI.
We had some heated discussions with their engineers about it because they wanted to move reset vector(!) to be owned by FSP-O before allowing actual firmware to execute (kinda like TF-A on ARM64).
Eventually everyone in the meeting went quiet and let me cook, it was a bit comical (me vs. three engineers from Intel), where I suggested extending CSME with it's own cache (as RAM is initialized much later) that can check status of EFUSEs and validate FSP signatures before releasing x86 cores from reset (which is nothing new, that's also what AMD is doing with PSP and PSB) if BootGuard is enabled and board went trough EOM.
In any case, they wanted to make it mandatory in the beginning. We pushed back, which brought Intel to negotiating table and made them change their minds. You can clearly see though that vendors don't care about openness of their platforms (unless money is involved) and real ROT is in the hardware.
Whoever makes the SoC and board, whoever rolls cryptographic keys *truly* owns the platform (or in other words - your hardware belongs to entity burning their signing keys into the "BootROM").
Circumventing those protections is not viable, saying "I'll buy second-hand" or "I'll buy from China" is simply... delusional. If every piece of hardware would become locked-down, you wouldn't be able to upgrade your hardware past certain point whatsoever. Buying from China might work for now, sure... but guess what would happen if China's SoC manufacturers would get equally as big as let's say, Intel/AMD/Qualcomm?
Yep, you've guessed it - same exact thing.