GOS has a camera app that works pretty well, but I prefer the proprietary Google one. You simply don't install any other Google apps or Google Play services in the same profile and remove its internet permission.

Now, it could technically only communicate with other apps that have Google libraries. I doubt these libraries include any code that does that. They are not that big, and we can reverse-engineer them very well nowadays with AI.

A targeted attack is still possible, but they won't systematically exfiltrate your pictures through other apps. That's way too much traffic. They would easily get caught if they did this, for example, on my network.