I built MeshLive, an open-source Android app for voice/video calls and live broadcasting over Bluetooth, without internet or servers.
Nearby phones can also relay broadcasts to extend their reach.
Inspired by internet shutdowns in India.
It's still a buggy, experimental beta, but I'm releasing it for testing and contributions rather than keeping it private.
Android APK + source:
https://github.com/MeshLive/meshlive-android