> There's a large debate whether a 'hybrid' kernel is an actual thing, and/or whether NT is just a monolithic kernel.
I don't think it's a concept that meaningfully exists. Microkernels are primarily concerned with isolating non-executive functions (e.g. device drivers) for stability and/or security (POLA) reasons. NT achieves virtually none of that (see e.g. Crowdstrike). The fact that Windows ships a thin user-mode syscall shim which largely consists of thin-to-nonexistent wrappers of NtXXX functions is architecturally uninteresting at best. Arguably binfmt_misc would then also make Linux a hybrid kernel.
Originally, Windows NT 3.x was more "microkernelithic" as graphics and printer drivers where isolated. NT 4 moved them to Kernel mode to speedup the system.
I don't think it's a concept that meaningfully exists. Microkernels are primarily concerned with isolating non-executive functions (e.g. device drivers) for stability and/or security (POLA) reasons. NT achieves virtually none of that (see e.g. Crowdstrike). The fact that Windows ships a thin user-mode syscall shim which largely consists of thin-to-nonexistent wrappers of NtXXX functions is architecturally uninteresting at best. Arguably binfmt_misc would then also make Linux a hybrid kernel.