My data:
Address field, that will always contain our State abbreviation:

What I want:
A pie chart in a dashboard, showing a count of enquiries by State. Example below:

This will actually be used on its own, embedded into an ArcGIS Hub site.
With arcade in a popup, I am familiar with how to pluck out the State abbreviation from the address field:

I have been struggling to try and build a Data Expression in ArcGIS dashboards to achieve this.
I have reviewed the expression in Github, but struggling to find one that I could reverse engineer to work for my fairly simple problem.
Can anyone assist in helping me understand if I can achieve this with a data expression?
The hosted feature layer is here.
The web map is here