If you do, can you plug in the USB and see if the Bios recognises and can boot from the OC USB.
The oldest copy I had on USB stick was 0.6.6, and it exhibited all the same BIOS problems.
This must be some kind of HW problem with my MB. I spent many hours trying to get the M Bios of the dual to go beyond the splash screen, but I never could. Plugging in and out the USB keyboard caused the debug led display go from A2 to B4 state - detecting a hot plug. But no amount of pounding on the keyboard would get the M Bios beyond the splash screen.
In the end I just re-flashed the B Bios, booted from the USB stick, reset the NVRAM. Next boot / reset hid the UEFI USB boot, so I disconnected my Windows SSD drive, removed a Time machine HDD, and just left the M.2 NVME OSX disk, then set the BIOS to boot ONLY UEFI drives, no legacy. Long story short, I was able to boot the 'Opencore' bootstrap on the NVME drive, add back the Windows SSD, and the HDD and using the F12 key able to boot from Opencore or Windows manager (on the SSD). The Opencore bootstrap sees the Windows drive, but when selecting it it boots to a blank screen from which it never returns. I suspect a conflict between IGPU and the RX580 discrete GPU, but at this stage I don't care. I simply use the F12 key to choose which OS to run.
My Z97x does run the latest Big Sur version (11.2.3 ?). All the regular features, bluetooth, iMessage, handoff, sleep all work.