macOS does not permit kernel extensions, because contrary to GNU/Linux they take ABI and kernel stability seriously, and are incrementally turning the OS into a proper microkernel, with all extensions running in userspace.
Do you have a source on Apple working to turn macOS into a proper microkernel? Couldn't find anything. Certainly Mach is a microkernel, but Darwin very much isn't. I do know that Apple has worked to expose some kernel-level hardware interfacing features in safer ways than giving full kernel extension access, but otherwise that's it?
How do you call a kernel whose drivers and extensions are all in user space?
WWDC sessions on that roadmap state quite clearly that is the long term end goal, all the kernel extension mechanisms will only be available in userspace, with one year transition for each subsystem after an userspace API is made available.
