• Consider Briar.

    Uses Tor. Works directly over Bluetooth/WiFi if the internet is censored or shut down. Decentralized, no accounts. No phone number required.

    Of all the options available, I feel like this one is the best suited to current threats (oppressive governments with all-encompassing surveillance, and the willingness to destroy critical institutions and infrastructure).

    The app is super barebones right now - feels like SMS - but it works. Main downside is that both participants have to be online at the same time (maybe group chats can work around this?), since there’s no servers.