Altough features like Top Shot (short video while taking pictures) and face retouching are available in the Pixel Camera app (from Play Store), they can’t be configured unless Google Photos is installed. For advanced editing features (magic eraser) GPhotos has to have internet permission.
The pre-installed GrapheneOS Camera isn’t as good as official Pixel Camera, but Pixel Camera works without any internet permission.
Imo there’s no point in using GrapheneOS while using Google’s internet-assisted editing features.