Having been there I think it's hugely inflated. Chongqing isn't really a giant city but a large city with a huge rural area around it that has been declared to be part of the city now. Not sure why that even happened. Maybe so that it can become a special trade zone without much political work?

30M of the 50M people of the municipality are urban, but yes it's more a large conurbation than a city proper.

Oh wow, according to wiki you are right and it's larger than Shanghai which I would have never thought. I guess the city feels smaller because of the central peninsula.