Updated post:
Here is my pictometry widget. It's just a way to open a link in a new window to your Pictometry.
Demo link ArcGIS Web Application
GitHub link to code: kevinsagis/Pictometry-for-WebApp-Builder · GitHub
Per the Read Me I will look into building the option to put Pictometry imagery into the popup inline as well. I've already had success putting video and other stuff in popups so hopefully this won't be too bad. Note also the capability to use your organization's internal EFS viewer with this as well! We use this as well as the Connect Online on Pictometry's cloud. Instructions for both of these implementations are below, including how to use the required php file.
Here's a Streetview widget that operates similarly:
Demo app link : ArcGIS Web Application
GitHub link - kevinsagis/Streetview · GitHub
***Update 5/18: New update posted. You can directly enter your server URL in the WebApp Builder in the widget configuration setup. For now it's just the Pictometry Online Connect (IPA). I will add the internal link field later today or tomorrow. See the Read Me.txt included for the common URL path formatting for Pictometry.