Nice dashboard!
It looks like you have one of your bases covered with the built-in functionality of the popup. You are missing the link for project details and the pie chart. For the link, I would suggest including it in your hosted feature layer's attributes as a txt field called "prj_link" and populate it with each projects website link and display it in your popup. For the pie chart, you could include it in another tab below the map frame and use your hosted feature service to create the pie chart specific to project stats.
Here is what I saw for your requested popup items fulfillment:
1. When you click on a point in the map and it contains a cluster, you see the screenshot below. This gives the total number of features (#1 callout) and then gives you a link (#2 callout) to browse the features.
2. When you click the "Browse features" link, you go to a scrollable list where you can click on an individual project in the list and get the details:
3. After clicking on one of the projects in the browse feature list, you can see details of the project:
Amanda Bishop, GISP