XNU, a hybrid kernel

XNU was originally based on the Mach microkernel. But nowadays macOS blurs the lines. Though some parts of macOS follow the microkernel spirit, other parts are monolithic. It's more complex than a "pure" microkernel. Perhaps a microkernel has less abstractions. But XNU is a hybrid kernel that nonetheless still employs the priciple of least privilege well - striking a balance between the two realms.