>>3macOS is loosely based on BSD but it's changed a lot and gone its own way since then
Apple contributes fixes to macOS, not BSD
FreeBSD is widely used, even if OpenBSD is not
Also the "security" of OpenBSD is a myth, it's not that there are no security issues, it's just that nobody is auditing the code to find it, since so few people use it to begin with
Linux seems insecure because it has so many people using it and so many people finding bugs, but that's because of how popular it is, and bugs get fixed pretty quickly