ReportDash DataStudio connector works in dual modes.

One can either pull in data directly from the 3rd party data source to DataStudio.
Or, one can first pull in the data to a ReportDash workbook, and use this workbook as a data source in DataStudio.

The later allows to blend data from multiple data sources, and to perform custom computations.
It also supports advanced filters.
(For e.g. One can filter based on campaigns using a pre-populated dropdown. )