Nope... but yes. No, because technically there's no way to 'bypass' the Gallery and set GPhotos as the default viewer (your camera isn't saving 'to Gallery', it's saving to a folder that the Gallery just happens to display). However, Google Photos IS a Gallery app, so pictures taken with the camera that go to the Camera folder, WILL be displayed in Google Photos. What you can control is if those pictures are saved to the cloud in Google Photos (Sync) or not, but regardless, if you open the Photos app in your phone, you'll still see all local files as you would with your stock Gallery app; Google Photos, however, will also show your cloud content in the main tab (there's a tab that will show only local folders, just like the Gallery app).