Thank You for info about Pi boot from GPU with closed firmware
Have you looked at the link I posted previously how they flash the firmware of CPU on laptops to remove UEFI to make it unclosed, can it be done to make high end gaming computers without UEFI, like you are seeking, or not ?

Have you looked at the link I posted previously how they flash the firmware of CPU on laptops to remove UEFI to make it unclosed, can it be done to make high end gaming computers without UEFI, like you are seeking, or not ?