Hello,
I am trying to see if it would be possible to unlock 4x4x4x4 bifurcation for the x16 PCIe slot on this motherboard. I can currently see only 8x8 and I feel like x4 should be possible for 4 NVMe drives using an adapter. Beyond that the ability to disable certain SATA ports and their features would be amazing if at all possible.

Use HEXedit and IFRextract to look for respective string values, usually modern AMI Aptio V core bios wont accept changes edited by AMIBCP.