Best to talk to a lawyer for specifics, but like non-compete agreements, NDAs often include things that can’t legally be enforced. The people wanting you to sign the NDA just hope you don’t know better and you’ll shut up.
If you know better, you can take their money and then disclose the facts anyway.
The boosting of propaganda and the identification, tracking and exploitation of government targets.
People in key government positions are still people like us and they love social media too. Having an app on their phone doing data mining can identify people of interest and then collect data, target and compromise them. Even without the app on a government issued phone they can identify key people using their personal phones and then target them for more sophisticated surveillance.