Nginx proxy pass(rewrite/ redirect) to specific page on app server

Currently,

https:// example.com proxy_pass port 8080 via Nginx to : https:// example.com/app/index.py

Configuration file :

location  / {

                  proxy_ignore_client_abort on;
                  proxy_pass https://ip_address_app:8080/;

/app/index.py is default loading page on application server.

Now, I would like to rewrite/ redirect or proxy_pass to non-default loading page from :

https:// example.com -- > Nginx --> https:// example.com/app/xyz.py 

I have tried rewrite , proxy_redirect and proxy_pass but it didnot work as expect.

I dont have permission to change anything on app server.

Please advise.

Thank you,