How can I group values by a field without losing String values?

[NygrenOhto]

I am trying to group a Table in ArcGIS Dashboards by municipalities by using Data Expressions, but the groupby function only takes the first string value it finds for each row and uses that.

Table I have:

Table I am trying to achieve:

Table I keep getting:

I cannot use the Grouped Values feature in ArcGIS Dashboards Data options as it only shows statistics for Value Fields and not string values. I have also tried solving this with Python but cannot find the correct way despite hours of Googling and trying.

[SimonGIS]

Having a similar issue.  Want to use GroupBy, but working with string fields and not numerical.