Yes I know macOS is POSIX certified. But the entire OS is certainly not FOSS and it limits me very much in what I can do with my computer, unless I switch off

Yes I know macOS is POSIX certified. But the entire OS is certainly not FOSS and it limits me very much in what I can do with my computer, unless I switch off its security completely. It's an all or nothing model. POSIX compliance is not something I actually care about. Having full control of my computer is.