You can embed any external content into a Pyramid Presentation/Dashboard as long as you have a unique URL to the content.  If you have installed the Power BI Report Server on premise or are using the Power BI Service in the cloud, you should be able to get a unique URL to their content.  By default, the URL from the Power BI cloud may not work without some configuration on Power BI (see their documentation for details).  Here is a link to the Pyramid help file describing how to embed web content in a Dashboard: 

http://help.pyramidanalytics.com/Content/Root/main%20help/apps/Present/Dynamic%20Web%20Panels.htm

However, as Yakov mentioned, we do not host Power BI content in Pyramid 2018 nor do we provide a means for browsing your Power BI content.