alt Hacker NewsThese kind of BIOS modding shenannigans is why I got interesed in Coreboot, so that enhancing a Firmware capabilities becomes possible without touching propietary tools/code.
Other similar mods included adding NVMe Boot capabilities to older Firmwares that didn't supported them so that you could boot from modern NVMe drives if you used some kind of adapter (As none of those Motherboards have M.2 Slots, but you can use them with a PCIe-to-M.2 adapter card). Also adding required stuff to get certain CPUs booting in Motherboard that were never officially supported (Depending on generation, could be as simple as adding new CPU Microcode).
These days you might be able to just point an AI at the original BIOS and tell it what you need done, instead of attempting to install a complete rewrite like Coreboot (which comes with its own limitations, the biggest one being that only a rather small subset of mobos are actually supported.)