An update this week to Google Photos for Android adds a handy shortcut that lets you jump from a just-taken photo to Google Photos, where you can edit and share the image. This means you don't have to exit the Camera app, open Photos manually, and then find the image.
To turn on the shortcut in Google Photos, tap to open the navigation drawer on the left of the app bar and then tap Assistant. Tap the Add Shortcut to jump from Camera to Google Photos.
The shortcut thumbnail appears on the just-taken image for about five seconds before fading away.