As mentioned before in this thread, I've implemented this for an early stage startup with some hundreds of thousands of users. It was a game changer in terms of helping our customers with some processes, and us understanding the shortfalls of our UX.

On one hand, I have a backoffice that gives access to the staff to everything related to the customers, but on the other hand I'm supposed to believe that being able to 'impersonate' a customer is this highway to hell? As long as an audit log is held about who did what, this can go a long way forward.

Are you Series A? B? A decacorn? Sure, implement whatever distributed tracing dashboard analytics data lake serverless microservice monitoring solution you can dream of. But this is good advice for early stage.