Making WiFi work on Big Sur unsupported Macs with “failed with 66” error

TRY THIS FIRST

HUGE DISCLAIMER, PLEASE READ IT:

Step Zero

Step One: remembering Volume Group UUID and preboot disk

Step Two: disabling authenticated root

Step Three: mounting volume

/System/Library/Filesystems/apfs.fs/Contents/Resources/apfs_systemsnapshot -s "BeforeWifiKexts" -v /Volumes/<Volume\ Name>

Step Four: replacing kext

Step Five: installing kexts

Step Six: creating snapshot and making it bootable

/System/Library/Filesystems/apfs.fs/Contents/Resources/apfs_systemsnapshot -s "WifiKexts" -v /Volumes/<Volume\ Name>
/System/Library/Filesystems/apfs.fs/Contents/Resources/apfs_systemsnapshot -r "WifiKexts" -v /Volumes/<Volume\ Name>

Step Seven: copying updated BootKernelExtensions to the Preboot

cd /Volumes/Prebootcp -r 1-2-3-4 1-2-3-4.beforewifikexts
cd /Volumes/Preboot/<UUID>/boot/System/Library/KernelCollections
cp /Volumes/<Volume\ Name>/System/Library/KernelCollections/BootKernelExtensions.kc .cp /Volumes/<Volume\ Name>/System/Library/KernelCollections/BootKernelExtensions.kc.elides .

Step Eight: final

Bonus Step: in case something went wrong

/System/Library/Filesystems/apfs.fs/Contents/Resources/apfs_systemsnapshot -r "BeforeWifiKexts" -v /Volumes/<Volume\ Name>

Immolate Improved