alt Hacker NewsI had to reinstall MacOS Lion manually recently, as Macs do not have a BIOS and require a MacOS environment to begin installing Windows. I was installing Windows on legacy Macs, because it gives me 30+ years of software and performs well, unlike MacOS (5 years software if lucky, unusably slow performance on older hardware). I intentionally did it all the hard way offline from a Windows host, so that I could replicate it without depending on someone else's flakey servers (which incidentally refused to serve me OS installer images)
I detest crummy Unix-style online stub installers and package managers, because the original downloads are always down when you need them, and it's much harder than it should be to force offline replicable reinstallation.
To my recollection on the machines that shipped with Lion (circa 2011) you’ll want to set up a protective MBR with the appropriate drive dimensions on the GPT, to get it to install windows like with boot camp.
To my recollection on machines with discrete GPUs this is what triggers the appropriate hardware configuration (BIOS boot, disabling the internal GPU and switching the MUX to only route via the AMD card)
But I do recall getting the internal GPU working with this trick https://github.com/0xbb/apple_set_os.efi