- Specify a new folder as directory for the GrapheneOS Camera in it's own settings.
- set storage scopes for GCam and Google Photos to access the DCIM > Camera.
Now you can use both apps together without leaking your GrapheneOS photos and videos.
How to use Google Camera / Photos on GrapheneOS
15 days later
For those wondering why you should do this:
post processing is done in google photos when viewing the image
10 months later
How to manage and edit all images from the files app?
Hint: AOSP Files shortcut to Images