@karthik palani Thanks for posting in our Q&A.
For Q1: Did you mean that you want the devices are in AD on prem and Azure AD? If yes, GPO enrollment is a good choice. Please refer to the following article to get more details.
https://learn.microsoft.com/en-us/windows/client-management/mdm/enroll-a-windows-10-device-automatically-using-group-policy
For Q2: It is more related to Azure AD and I know little about it. Let's wait for the Azure AD engineer involved in this issue.
For Q3: To avoid any misunderstanding, could you please describe more details? If possible, please tell us what you want to achieve.
If there is any update, feel free to let us know.
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