Hi @cgoodman3! Yes it's possible - you will need to set the column up as a segment (in your case, set up "Customer"/"Customer ID" column as a segment in Admin Portal).
You can refer to this help desk article for more details - under Data Types: Segment.
This way, Auto Insights will automatically create a measure called "Number of Customer"/"Number of Customer ID" - which is a distinct count of the values in that column. Hope this helps!
Cheryl
Customer Success