@Ahmed Alshatawi, Thanks for posting in Q&A.
Based on my research, if you we decide to use Device Preparation Policies, we should remove the main Autopilot group from the deployment profile and Enrollment Status Page, because Windows Autopilot and assigned a deployment profile will prioritize the Autopilot profile over the Device Preparation policy.
Windows Autopilot device preparation user-driven Microsoft Entra join is a solution that automates the configuration of Windows on a new device without the need for IT intervention. Normally the device is delivered directly from an OEM or reseller to the end-user Windows Autopilot device preparation user-driven deployments use the existing Windows installation installed by the OEM at the factory. It improves the onboarding experience by providing a profile experience to deploy configurations efficiently, consistently, and remove the complexity out of troubleshooting. Windows Autopilot Device Preparation is a feature designed to streamline device provisioning by automating the deployment of applications and configurations during the out-of-box experience (OOBE). It enhances the traditional Autopilot process by providing near real-time deployment status and monitoring, thereby reducing IT overhead and improving user experience. So, there is not an option to set a naming convention or exclude a group.
During the out-of-box experience (OOBE), a user authenticates with their corporate credentials. If there's a Windows Autopilot device preparation policy assigned to the user signing in, then that policy is delivered to the device. It then determines the configuration that needs to be applied to the device based on the settings configured in the policy.
Here is a link about Windows Autopilot device preparation user-driven Microsoft Entra join process
Hope above information can help you.
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