Some notes about my USBopencore 4.2 spoofing version, if after beta 6 installation you patched some kext (typically the Wifi and Sound) that means these
kernelcollections
changed compared to a "sealed system apple stock":
BootKernelExtensions.kc
(easily recoverable),
SystemKernelExtensions.kc
(size 500 MB or more, not easily recoverable, but more easier if you have an unsealed system or a working "sudo mount -uw /") and
AuxiliaryKernelExtensions.kc
(that are kext installed on /Library/Extensions/ not useful for Wifi or Audio patches).
Probably some mismatched kernelcollection is recoverable from a BigSur recovery through:
kmutil invoke-panic-medic
or
kmutil trigger-panic-medic --volume-root /Volumes/<YourVolumeName>
Anyway regardless of "SystemKernelExtensions.kc" that is also updated when kext are patched, this should fix an usbopencore booting for the BigSur's Preboot:
https://forums.macrumors.com/thread...unsupported-macs-thread.2242172/post-28948321
I know It's weird but you need a separate snapshot for opencore, because the snapshot booting used for "apple startup manager" is tagged for a different UUID root, but using my previous step from single user mode should fix this even when using a kernelcollection with patched kext.
My USBopencore setup could work also for other machines, but for those who have a MacPro I advise to follow this thread:
https://forums.macrumors.com/threads/opencore-on-the-mac-pro.2207814/