Generate/Refresh Iframe in Panel after Button Press

I’ve got an interesting one that I’m struggling a bit with but feels possible.

I’m looking to create a pages tab (easy enough itself!) for the Panel that lets me push a button and then create/recreate or refresh (I don’t really care how it works) an iframe underneath. The use case is that I want to pull the URL of the published page and run that through a test that’s hosted on another site, all without leaving the page tab.

I see this, which gives me hope:

Is this possible? And if so, any hints to get me started on the code?