I will admit, and I would think pretty much everyone would agree.
It would be nice, perhaps in the future, perhaps with better hardware on-board, to have the ability to create an area inside alexa that was local to just that device.
Ideally still not only to the device, but also to a specific user.
I have been on the phone to a company many times, and they say. "Before we go any further I'd like to ask you for some letters from your password"
It would be nice if I could ask Alexa for this help, perhaps one day