@[email protected] To expand on the response from [email protected], I've found that most FOSS camera apps pale next to the stock Google Camera app. So the way I've approached it on my GrapheneOS Pixel is to install G Camera and Google Photos, but I've sandboxed them and only given them access to the specific storage areas they need. I've added its DCIM folder to my SyncThing, so all my photos are available on all of my devices without having to switch on Google's library syncing.

All in all, I'm pretty happy with that setup. I do use a couple of other camera apps, but that's mostly for manual camera control and RAW output. For simple point and shoot, Google's stock camera app is really good.