But we'll not know unless they open source it. chuckle

Darwin is open source. Here's the repo for their kernel: https://github.com/apple-oss-distributions/xnu/tree/main. The userspace stuff can be found here: https://github.com/apple-oss-distributions/distribution-macO.... Some stuff that's missing from those links, such as launchd, can be found here: https://github.com/apple-opensource?tab=repositories