Parts of it are. The kernel is derived from a Mach microkernel (an experimental kernel in the 80s, which was theoretically supposed to allow different OS personalities to coexist in the same system, sharing resources; macOS’ Darwin/XNU kernel doesn’t implement this capability in full, but you do get the Mach Ports interprocess communication mechanism, and a BSD UNIX personality permanently attached).
Parts of it are. The kernel is derived from a Mach microkernel (an experimental kernel in the 80s, which was theoretically supposed to allow different OS personalities to coexist in the same system, sharing resources; macOS’ Darwin/XNU kernel doesn’t implement this capability in full, but you do get the Mach Ports interprocess communication mechanism, and a BSD UNIX personality permanently attached).