Ultimately, it depends on if it is an issue in terms of your threat model. I have noproblems with people using some proprietary tools. Sometimes you do need things to just work, unfortunately.

I don’t know if Google Camera would share the information with Sandboxed Google Play. However, something to be careful of, is if you have two apps by the same developer (Google in this case), and you have network permissions for only one of them. The developer could share those permissions with their other app. TheHatedOne did a podcast episode on this. He checked with a GrapheneOS developer beforehand, and found, that this is possible.

I wonder how many users Matrix has?