Hello Amanpreet, Have you explored dash studio within appdynamics custom dashboard section? I doubt if your use case is feasible because as per my understanding data pull happens per application in most of the cases in appd.
There are two things you may try - 1. Use dash studio which allows you to out application in drop down on top and have one widget on main body to show the events generated for that app. (I haven't personally tried that but If I remember it correctly this feature of app selection was there)
2. Like we are doing, publishing metrics and events from appd to seperate datastore and use some other BI tools like grafana/edge to display all at once.