Comment by Aissen

Not exactly, before now they added a feature to boot any arbitrary OS. Yes, it had to be a Mach-O, but they didn't need to add this AFAIU… See the kmutil doc: https://twitter.com/marcan42/status/1333126018068955136

https://keith.github.io/xcode-man-pages/kmutil.8.html

I recall an Apple developer saying that no one internally believed it would get any traction, but they did it anyway.