GrapheneOS is a privacy project with major privacy enhancements including Contact Scopes, Storage Scopes, secure paste and much more. It doesn't connect to any third party services by default and has a very limited set of default connections which are documented and can be controlled by users.
GrapheneOS preserves the standard privacy/security of AOSP by keeping up with updates and enabling all of the protections. It also provides far better patches than AOSP and the Pixel OS.