Idea: Add a "Filter Datasource Field" object that lets you set the value to filter, then map that to the field(s) to filter in one or more datasource. 

Example: When working with reports that pull data from multiple datasources, I tend to use parameters for the shared filter value, and groups to apply that filter to the different datasource objects. However, this requires adding these filters to each group, one at a time. With a multi-datasource filter option, I could use that at the root-level of the report to filter every datasource to the same granularity first.

For example, Datasource A has a [Month Year] field, and Datasource B has a [Mo Yr] field. I need to filter them both down to "Jan 2026". So for the expression, I enter "Jan 2026". Then I add an entry for the [Month Year] field in datasource A, as well as an entry for [Mo Yr] field in datasource B. Upon running the report, both datasources will be filtered down to the same value.