On the order page the customer's name in Billed to (top right) and again in the Client Details card links straight to that customer's profile, and the View Customer button at the bottom of the Client Details card opens it too. In the Customer Orders list, the User column is also a link to the customer's profile. Going the other way, you can see a customer's orders by opening the Customer Orders list filtered to them (the list can be opened pre-filtered to a single customer), and in the current version the customer's own website account shows their own order history as well.