ok sorry i didn't tell you before, but those configurations you told me to do, i had done them before and the result doesn't change, so i tried to change with little success. so i put builtins without the opencanopy driver, this is because i noticed more reactivity and no sudden crashes. Imac is now set correctly with imac20,2 and ig-platform-id was already set up as you wrote it, but occasionally crashed. the device id can be found under a pci root entry, as suggested by the opencore manual for cometlake cpu and it works perfectly. however, I send you the updated EFI file, and working for the boot part.