How good is the new Pixel 3 camera? Well, I just did a comparison between a Pixel 2 vs. Pixel 3 cameras and the results are very interesting. It seems that most of the improvements on Pixel 3 back camera is from better software processing but I do not see much difference in the camera sensor/lens. Eventually, you should be able to get all new Pixel 3 camera features on your Pixel 2 or Pixel 2 with a modded APK.
You can download the original photos here and compare them yourself.
Note: The Pixel 2 has Pixel 3 Camera APK installed, you can see how to install the Pixel 3 Camera here.(works for all Pixel, Pixel XL, Pixel 2, Pixel 2 XL, and Nexus 6P)