[MBCook]

My understanding is Apple uses Linux a lot internally for server stuff. Wouldn’t surprise me one bit if it was just Linux machines running LLVM and their other tools.

Perhaps the stuff runs on MacOS in VMs for the best compatibility, but I’m not sure that’s strictly necessary.

[mrweasel]

The iPhone apps where already cross-compiled from AMD64, before the switch to the Apple Silicon. It might not take that much to do the compilation on an Linux server, regardless of the underlying hardware.

There is something weird about a company that makes it's own hardware and operating system using something completely different in their datacenters. However I don't think that macOS have the tooling required to large scale installation required for something like this.

[pjmlp]

Once upon a time they did.