How do you maintain "Brand Authority" when your work is hidden behind NDAs?

[Btaliat]

There can still be logic on how the freelancers can show and promote themselves even when they are bound by the NDA( Non-disclosure Agreement) without getting into trouble. There is a way the freelancers can showcase the process by which they completed the task without showing the final products of the works. What do you think about this? Some can even show social proof without naming the names of the clients. Share other ways below..