> Look at Apple's proprietary forks of all the BSD stuff
What forks of what stuff?
What forks of what stuff?
Here's the kernel, including all the BSD stuff:
https://opensource.apple.com/source/xnu/xnu-7195.141.2/
You can compile it yourself and run macOS with your own kernel build. Here's a blog by Apple's head of XNU development explaining how that works:
https://kernelshaman.blogspot.com/2021/02/building-xnu-for-m...
You made a claim about "proprietary forks of all the BSD stuff". The kernel is open source. The rest of the OS is written from scratch by Apple, and originally by NeXT, and is not a fork of anything.
Are you standing by your original claim?