If I were NSA, I would create a "private" browser and a "private" "secure" email service and then just sit back and harvest all those "private" data.

#honeypot

Mandatory pigman quote:

“If you have something that you don’t want anyone to know, maybe you shouldn’t be doing it in the first place, but if you really need that kind of privacy, the reality is that search engines including Google do retain this information for some time, and it’s important, for example that we are all subject in the United States to the Patriot Act. It is possible that that information could be made available to the authorities.” - Erich Schmidt, former CEO of Google

Is Proton secure? Is Duck Duck?

I have no idea, but I would not bet on it.