@blackdbird
Everything I have done to make iMessage work on my PC is on the Dortania website "
Fixing iMessage and other services with OpenCore".
1. Serial number
I use a serial number appropriate to my SMBIOS. Generate a few with
corpnewt's GenSMBIOS tool and check them on the
Apple Check Coverage page to choose one that displays the message "We're sorry, but this serial number isn't valid." Another option is to choose a number that displays the message "Purchase Date not Validated" but has the disadvantage that it can be activated at any time on another Mac and cause interference with Apple services. What to avoid are numbers with the message "Valid Purchase date", these are already or have been activated on another Mac.
2. Ethernet as en0
I have the ethernet card as en0. If you only use Wi-Fi and you have Eth disabled or does not exist, you can use
NullEthernet.kext and
SSDT-RMNE.aml to create a fake Eth that can be assigned the BSD name en0. If you only use Wi-Fi and you also have Eth enabled, you also have to try to make Eth en0.
3. MAC address as ROM
I don't need to have the MAC address of my Eth card in config.plist because iMessage works fine without this option, but if necessary, you have to fill the ROM key in PlatformInfo with the MAC address (only numbers, no other characters).
4. NVRAM active
I have NVRAM native thanks to
SSDT-PMC.aml, without this option it is difficult to get iMassage to work well.
It is useful to review the final part of the Dortania guide (Clean out old attempts, Verifying your work one last time ...).
Anyway, I have not left that guide from the creators of OpenCore and with it iMessage app works well. I don't know what else to say, clean out old attempts and follow the steps one by one because you have to get it.