Your concern is valid, COINTELPRO never went away https://en.wikipedia.org/wiki/COINTELPRO. However there are a LOT of people who don't have a network and need to build one. The OP that I'm replying to went to a small town protest. It's completely valid to network at a corner in a small town square.

Most importantly, segment all comms. Have a friend group, an organizing group and a public group. If you're able sign up for a burner number. https://www.phreeli.com/ or any of these apps https://beebom.com/best-burner-phone-number-apps/ Obviously practice due diligence and only sign up for what you think is applicable.

Third spaces are disappearing and they were always the place where revolutions were started. A protest is a completely fine place to meet organizers, other people who are aligned and people who have experience in the movement. Resources to organize can be found here https://www.fiftyfifty.one/organizer-resources Similarly you can find people who are aligned here https://www.fiftyfifty.one/groups

Paper is a perfectly fine way to setup one time pads https://en.wikipedia.org/wiki/One-time_pad, or something you can destroy by burning or eating. Currently people mobilized in Minnesota are using it to great effect. They're writing down the addresses of people that need food aid and making sure to not share them over facebook or store them in their phone. If caught, the volunteers delivering much needed food are instructed to eat the paper.

How to organize a rapid response from a very high level with further detailed resources. https://southerncoalition.org/resources/rapid-response-101/

Basically what I'm getting at is with Palintir working so closely with ICE and all of the other electronic surveillance they have, ICE knows if you're at a protest. They already know pretty much who is doing what. The only way we win is if there are too fucking many of us helping to make those databases useless. When every one is on the list nobody is.