@binauraloptions is right, it really isn't difficult.
Really is just a matter of using gibMacOS or a real mac to download the installer, then you use the same suite to create the installer (I'm assuming your on windows right now). Once the stick is created, you'll need to copy the efi to the EFI partition (gibMacOS should leave it mounted for you. Delete the EFI folder n there and copy across the EFI I made). If your using a real mac google the createinstallmedia method for big sur / catalina - its right on the apple help communities, then use MountEFI to get the EFI partition mounted and drop the EFI in.
Load up propertree, open the config.plist and GenSMBios and create a MacPro7,1 or iMacPro1,1 serial, and copy the details into the Platform Info section.
Finally, drop in a kext for your Ethernet if Lucy or Smalltree won't drive your ethernet, and move Lucy and Smalltree out. Installers done on windows NEED an internet connection, and installing will seem slow as molassas, as its downloading while installing. Use propertree to refresh the OC directory in the EFI folder so the Ethernet kext is added. If your Ethernet works on either of the kexts, just leave them there. It won't hurt if you forget to remove them, they won't load if they have nothing to attach to.
Now boot the stick with the target computer and see how you go.
The Bios settings are farily easy
Above 4g Decoding off (or remove npci=0x2000 from boot-args)
PCI Link speed for PCIE-01 3x (experiment, if you can get away with 4x or auto, all the better)
XCHI handoff on
ECHI handoff on
Set sata controller to ACHI (if booting from a SATA SSD/HDD)
If you get stuck, look at the verbose screen and see where its stalling, then head to (os x version) installation on this forum and post a question AFTER doing a thorough google of the issue.
And yes I have spent time in the copilots seat of a twin commuter and operated some of the controls for the pilot to ease the workload. As a bonus my instruments had a HSI that was all over the place. He said the instrument was inoperable, and not to worry.
phew