Unable to create a bootable USB for BigSur - OpenCore

Hey all really hoping someone from the community can help me out.

Im running Catalina on Opencore fine but needed to use MacCatalyst app therefore needing 10.11 (BigSur)

Ive read & reread the dortania guide here https://dortania.github.io/OpenCore-Install-Guide/installer-guide/mac-install.html

Im going to put BigSur on a separate SSD but most everything else is exactly the same so the same EFI folder should be ok to use on the BootUSB and Eventually EFI of new BigSur SSD ( I think i might have to change/update the serial number on Big Sur but not sure)

Im able to create a USB using createinstallmedia without errors then mount the EFI of Big Sur Install USB to place my EFI ( Catalina) into the EFI (Big Sur Install USB)

but for some reason the usb is never recognized by opencore bootmanager as being bootable.

Ive tried multiple USB drives same result.Ive also tried just putting a fresh EFI from the latest OpenCore release but still no dice.

What am i doing wrong/missing?

Thank you any and all advice!