GrapheneOS is a privacy project and heavily improves it with important privacy protections including Contact Scopes, Storage Scopes, secure paste and much more. It preserves all of the standard privacy and security of AOSP while greatly improving upon both.

GrapheneOS doesn't connect to Google servers by default and avoids integrating any privileged access for either Google apps or partial replacements for those. The main operating systems integrating microG included always granted privileged access for microG, Google Play executables downloaded by microG (droidguard) which run with the privileged access it's granted and other Google apps including Android Auto.

The operating systems you believe are privacy projects greatly reduce both privacy and security compared to AOSP through not keeping up with standard patches, not providing important standard privacy/security protections and adding problematic services.

Lagging behind the already inadequate standard privacy/security updates by months and even years isn't compatible with providing reasonable protection for user privacy. Only a subset of the issues Google classifies as High or Critical severity are backported to the older releases of Android those are usually based on. Taking many months to move to newer releases is much more problematic than it appears. The backports to those older releases also get applied with a substantial delay. Firmware and drivers are usually not kept properly updated even when those are regularly released such as for Pixels. Many standard privacy and security protections are missing or disabled. An assorted of third party services are added too.

That's very false. GrapheneOS is primarily a privacy OS that also focuses on security to provide strong privacy.

Sandboxed Google Play has no privileged permissions, which means that those apps have the same permissions as any other apps you can install on Android, meaning the same restrictions.

All that plus the fact that Sandboxed Google Play is a better approach because it offers better app compatibility and is more secure. microG doesn't meet the project's standards.

GrapheneOS is and always has been a privacy first project.