Actually Google Night Sight is great.
It's well beyond what an iphone can achieve in difficult low light situations.
The example shown by Google it's not exaggerated at all.
How about enhancing other UI features..? Never understood why there is such a heavy emphasis on the cameras. I know social media is big...but so many other features missing.
How it sits is a key aspect of the phone's functionality to me. I often use the phone while seated in a cafe etc, and often end up typing relatively long emails or chats. It's annoying that the phone rattles around when it's used on a flat surface.
An advanced camera, however, I don't care too much about. As long as it can reliably take halfway-decent pics, I'll be quite happy. I'm not a professional photographer.
Not sure what do you mean by saying "all of this". In terms of augmented reality, currently both Apple's ARKit and Google's ARCore use one lens and "AI" (actually, computer vision algorithms such as SLAM) to do their magic.