> iOS and iPadOS share a kernel with macOS, and for all I can tell, so do watchOS and tvOS.

Even worse is that iPadOS and iOS are effectively the same operating system, one ships with a phone dialer and the other ships with UI tweaks for tablets. I would not be shocked if they are built from the same source tree.

i think the ios and centos people are putting on airs because they wish they were ken thompson

unlike, say, illumos, macos doesn't contain anything genetically descended from the v6 unix kernel; the darwin kernel is mach, with chunks of freebsd grafted into it, chunks that carefully reimplemented without copying the functionality in original unix

by contrast, 'chromeos' and android run on fairly normal linux. they even keep up with linus's tree, and though they do have their own patches, they try to get them merged back into linus's tree