On attempting to refine the config file, I found that WEG does prevent a boot into bare metal BS (but is okay for Catalina). If left enabled, then one must enter the boot-arg "-wegbeta".
Similarly, AMDRyzenCPUPowerManagement kext prevents a bare metal BS boot (but is okay for Catalina). Lilu, VirtualSMC, AppleALC, the ethernet kexts, the AirportBrcm kexts and NVMeFix are all okay, using latest versions.
booter-fileset-basesystem and booter-fileset-kernel are not required as shown below.
Most importantly, this config.plist file boots into both Catalina and Big Sur bare metal (one config to rule them all...).
Booter and Kernel Quirks:
NVRAM:
UEFI: