Is there a dashboard for the AV signature version (vdf) in the console UI?
No. There is not currently a dashboard for Signature Status. To see which devices are up to date or not, the "Signature Status" filter on the Inventory > Endpoints page can be used. For additional filtering / chart creation, the "Export" button on the inventory page can be utilized. From there another tool (such as Microsoft Excel) can be used to create a pivot table / chart from the exported data.