The best resource is to avoid them all together if anyone wants real private conversations. Good old fashioned meetups are the best. Otherwise, there’s always a backdoor to discovery. Depending on encryption methods, “they” will have to work harder to determine information. But give them enough time/technology and they’ll figure it out. If someone is a whale, you’re worth their time. If someone is a goldfish, they don’t have the manpower to be bothered.

With that said, if someone is adamant about the best digital privacy, simply be one step ahead. You need people on your team smarter than the people on their team. It’s that simple. Rather than focus on the vulnerabilities and try to fix them, Create better technology. Develop better algorithms. Design better encryption schemes. 8 billion people in the world. Get the better squad. May the best man/woman/(or government) win.