Implement a customer survey upon logout for C8Y

We`re looking for possibilities to integrate an external survey Information to the customer after C8y login or logout? DTAG would like to get some information/feedback from their customers.
Note: This is urgently needed as due to some miscommunication the customer was led to believe that this is already possible thus has developed an external URL with their survey and have raised changes with MaSe to request enabling/connecting those.