On the PB Admin > Developer Tools > Configurations page, add a "? Check Usage" button. Similar in functionality seen on the PB Classic Configurations page.
When a specific feature/chain/layout was selected, and the "? check usage" button was clicked, then display a linked list of all the Pages and Templates that had an instance of that item present.
Additionally, for a selected configuration item, you could display "This Feature is used" (yellow box) or "This Feature is not used" (green box), before the button is clicked.