In order to get iMessage and FaceTime to work on Big Sur, we need to have a valid account with Apple. There are a few things we need to get working before login to iCloud.
1. iMessage Debug must be free of errors.
2. en0 must be IObuitin with network hardware of the system. Use ioregistryexplorer to check.
3. Serial # used must not matched real mac registered serial #.
4. nvram must work. Do some tests to make sure it’s working.
5. Make sure to have a good SMBIOS with ROM mac Address of En0 and spoof is checked.