How would you add ShellX64 into Uefi firmware?

Hi,
Was wondering how would you add a Uefi shell efi utility into an Ami bios rom such that it could be loaded by function key or boot menu without needing an efi partition? The Ozmosis bootloader has something in effect so it’s doable if anyone knows how?

Thanks

Does your BIOS menu have anything like "Launch EFI Shell from filesystem device"?

I was able to add a built-in EFI Shell to my ASUS Z97-A UEFI BIOS by extracting Shellx64.ffs using UEFITool from a the UEFI BIOS of a Z97-based MSI motherboard then updated the PE image using the latest Shell.efi binary from TianoCore EDK II on GitHub. The "Launch EFI shell from USB drives" menu item of the UEFI BIOS now loads this built-in EFI Shell application.