You can install the google camera. Both camera apps can be installed at the same time.
If both are installed at the same time and an external app wants to launch a camera app the OS will prompt you to choose one. Like pushing the lock button twice.
If you choose to use Google Camera over GOS's camera, you can always disable GOS's camera in the app settings. You can reenable anytime you want. Disabling does nothing except make the app unavailable in the current user profile. It'll be available in any other or new profiles.
Since Google's apps are all closed source, there's no way to know what kind of data they collect with GCam. Your best bet is to just revoke the GCam's internet access.