How to view frame source without using the button?

I want to make a custom chat app for me and my friends at school, and I found a good template here. The only problem is that I’m using Apps Script for this, meaning I don’t have advanced options. (I would use a different website hoster, but Apps Script is unblocked in our district.) I want to view the direct source of the app frame, but our district blocked the View page source and View frame source options. I know the trick of using view-source: in a url like view-source:https://stackoverflow.com/, but I was wondering if there was a way to get the frame source using a URL tag? I tried importing the code to Apps Script using the provided boxes and referencing CSS files on a GitHub repository, and everything was working well until I realized that jQuery wouldn’t import.