Here is an ISO to Make Things Really Easy
This is mostly intended for personal consumption and GitHub is a free backup solution, but I will make it public so the wider world has access to Advanced BIOS on Lenovo Legions (at least for Lenovo Legion 5 Pro 16irx9).
This is an ISO file, which when burnt (using the utility of your choice, I use Linux and am terminal competent with it so I use dd but have heard great things about balena-etcher, rufus and other utilities to ease the use of lsblk to determine which drive and dd if=/dev/sdX of=/path/to/iso.iso for those adverse to those to commands).
AGAIN YOU CAN BRICK YOUR SYSTEM IF YOU DON'T KNOW WHAT YOU ARE DOING WITH THEM, BE CAREFUL AND DON'T BLAME ME FOR YOUR MISTAKES. I TAKE NO RESPONSIBILITY FOR WHAT YOU DO WITH ADVANCED BIOS BUT AM PROVIDING YOU THE OPTION IN AN EASY TO UTILIZE MANNER.