I have not yet used the Dashboards app, so will first like to find out if this is possible.
Similarly to the "Summary Statistics" ArcGIS Pro calculator (accessible by right-clicking a field and selecting "Summarize"), is it possible in Dashboards to get a sum of the first value of a field ('Total_Acreage' in our case), based on a Case Field ('GPIN' in our case)?
Example calculation attached.