Loading kernel extensions with kexutil is still not possible.
Launching "sudo kexutil -v" followed by the path of the kernel extension to be loaded fails:
Failed to load /Library/StagedExtensions/Library/Extensions/LittleSnitch.kext - (os/kern) protection failure.
(kernel) Kext at.obdev.nke.LittleSnitch failed to load (0x2).
(kernel) Failed to load kext at.obdev.nke.LittleSnitch (error 0x2).
This is an example, but happens with other popular apps like Turbo Boost Switcher kernel extension, BitDefender, etc.
Is there anyone else suffering the same behavior?
Just filed a bug to Apple with this in any case: 41266208
Just updating to let you know that Apple fixed the issue on beta 4 and all of those apps are again working on Mojave!