Cool that you ask your question here. Sure, it is possible to do what you want.
To achieve this, you go to the “Ticket” board and create a column with the type “Link Item to”. Then you select the board “Customer” and you have to select “link only one item” and “Show column in other board as well”. After that, you can link the tickets to the respective customer and see all linked tickets in the customer board.
Thanks for the reply! This did get me most of the way there. Once I linked the boards - I added an additional formula column to count the number of tickets.
I used this: SUM({Customer Tickets#Count}) where Customer Tickets is the column I added to the Customers board, if that makes sense?