If you really need a phone on you, get a burner phone with a prepaid card not linked to your person. But remember, MITM attacks are possible and the police can intercept your traffic and in some cases even compromise your E2EE services (if the key exchange takes place on a compromised spoofed network, see stingrays [1]).
If communication is necessary, get a meshtastic device. It’s not the most reliable, and the channels can be jammed, but no one will bother with that. Because they work on usual IoT/smart home appliances frequencies, there is so much interference in cities that triangulating your position in a crowd of people isn’t very realistic.
Do not bring your phone with you to a protest.
If you really need a phone on you, get a burner phone with a prepaid card not linked to your person. But remember, MITM attacks are possible and the police can intercept your traffic and in some cases even compromise your E2EE services (if the key exchange takes place on a compromised spoofed network, see stingrays [1]).
If communication is necessary, get a meshtastic device. It’s not the most reliable, and the channels can be jammed, but no one will bother with that. Because they work on usual IoT/smart home appliances frequencies, there is so much interference in cities that triangulating your position in a crowd of people isn’t very realistic.
[1] https://theintercept.com/2020/07/31/protests-surveillance-stingrays-dirtboxes-phone-tracking/