gdsports:
Try a Teensy which does a better job of emulating USB devices.An alternative is to start hacking the AVR board package files to change the USB keyboard device descriptors. If you dump out the USB descriptors for a Leonardo, Micro, or Pro Micro emulating a keyboard and compare against USB descriptors from a real USB keyboard, you will see many differences. The differences are why Arduino keyboard emulation does not work in the BIOS.
Thank you for the detailed explanation.
Cheers!