I have a bluetooth keyboard that's originally connected to my desktop PC. The problem is that I can't use it in BIOS or to select different boot options at grub because the bluetooth drivers aren't loaded up yet at that point. I'm trying to use a Pi as a relay point where it will always have the bluetooth keyboard paired to it, take in the keyboard commands, then output it as a USB keyboard (it'll be connected to my desktop PC through USB).
I found this guide (among many others) that tries to do the opposite, but couldn't tell if I can flip it around. https://www.gadgetdaily.xyz/emulate-a-bluetooth-keyboard-with-the-raspberry-pi/
Is there a known way to accomplish this? Is there a more straightforward method? (I'm new to raspberry pi and peripheral IO, but familiar with python and linux in general)