I've read the article about what's new in 2021, and was impressed by the ability to join existing ArcGIS server service to non spatial data, by any common attribute.
Is it possible to symbolize the features, by the data in the non spatial table?
It would be great to show the company regions (polygons) by the data from Power BI.
At this time you cannot style the map based on the joined data. There should be an enhancement request or idea for this already, but you don't see it.. feel free to create one!