People use their phone today to: Manage 100k+,1M+ bank accounts, 2FA, secret messaging, sensitive media, medication, credentials and more. This privacy feature makes a lot of sense. Give it a couple of iterations and I think this will be the standard in business. It never made sense to me the trust that we put on no one looking at the contents of a display at the same time as us.
I've seen this with laptops that came with integrated electronically controlled privacy filter. They were nice but eventually the added cost, complexity, and lowered image quality didn't make them a popular choice even for enterprise users. I think only HP still offers them from the big brands, Dell and Lenovo don't do it anymore.