I'm pretty convinced that the only way to do this is through enforceable legal restrictions, not through technology. This is because those with deep pockets (nation-states and multinational corporations) will always have the technological edge over any average user.
In addition, any operating business has to operate under the laws of the host country, see what happened with Lavabits and its refusal to hand over email encryption keys in 2013:
"The court ordered Levison to be fined $5,000 a day beginning 6 August until he handed over electronic copies of the keys. Two days later Levison handed over the keys hours after he shuttered Lavabit."
The only way to stop nation-states and multinationals from spying on everyone and everything is to make it illegal for them to do so, and to enforce those laws with meaningful punishments.