Configuring different apps in Nginx using same domain

I have an ecommerce application running 2 applications. App 1 (example1.com) is written as react.js and built as a normal html site. Nginx is serving this on port 7000. App 2 (my.example1.com) is a java application and nginx proxies this to tomcat using a different port.

I now need to be able to make cross app calls between these 2 applications and maintain certificates and cookies between them. Our thought is to move my.example.com to example.com/app2 thereby putting both apps on the same domain which we believe will maintain the certificate and cookies.

I however am not sure how to configure nginx for app2 (example.com/app2)

Can this be done? Examples would be greatly appreciated.