Hello, what I can tell you is don't get nervous to start from scacth.
Here you'll find all you need to create a new USB drive, EFI and installer: https://github.com/aleixsr/Ryzentosh
My EFI works fine to run macOS installer, install it and run Mojave, Catalina or Big Sur.
Currently I'm under Big...
I have news!
I upgraded (using pendrive installer) from Catalina to Big Sur 11.0.1 and it worked like a charm! (No "EXITBS:START" error)
Keep using provided EFI to upgrade (the same I use to boot normally)
Sleep Works Out of the Box!!! Nothing needs to be changed! Using exact same...
Intel AX200 Wi-Fi is working fine using https://github.com/OpenIntelWireless/itlwm but performace sucks (like they asy XD)
Also I got great FPS on gaming and sleep working under Mojave.
You can get all my job here: https://github.com/aleixsr/Ryzentosh
This guy tells sleep is working with same board but isn't ITX form factor:
do you think it should work?
I tried his EFI...