Thanks! I compared our EFIs and just noticed I was carrying additional kexts that I should not have been supporting anymore so I got rid of those. I copied how you have set up ACPI in Clover Configurator sans the custom SSDT.
The above got me using the iMac18,3 SMBIOS, which I couldn't get working with DP, I'm thinking its one of your kexts. The only kext you have that I didn't was Shiki though which I thought was already integrated with WhatEverGreen kext.
Despite all of the above, shut down still didn't work. As an additional issue ,when I put the computer to sleep, it looks like only the display turns off as the keyboard, case lights and GPU fans still spin.
Was gonna call it a night until I found a thread here:
https://www.tonymacx86.com/threads/solved-mojave-reboot-when-waking-from-sleep.261061/
Basically, it has you delete com.apple.powermanagement files from /Library/Preferences. Everything works great after!
So I don't know what wasn't working but its fixed for now. Have you updated to 104.2 BTW and is a direct update okay?
Thanks for all your help man you have been a selfless and awesome resource!