Seoul to Hong Kong via Pudong and Hongqiao

I am looking to visit family in Hong Kong. I want to book a ticket from Seoul to Hong Kong, and then Hong Kong to Busan.

This flight goes from Seoul to Hong Kong, with a layover in Shanghai. However, this layover involves arriving at Hongqiao, and changing airports to Pudong. This is a 9 hour layover.

As a US Citizen, will I be valid for gaining entry into shanghai for that time to have lunch and go onward to Pudong for my flight out? Thanks so much for your time and effort.