Using #arduinonostr library its possible to make a #nostr mesh-network of cheap microcontrollers.
A node is both dumb relay and client, it looks for other nodes nearby and connects to them over ble/wifi to share notes. Notes are push/pulled over webserial to a device (phone, whatever).
As long as the microcontrollers are always looking for new connections, the mesh will be self-healing.
https://github.com/lnbits/arduino-nostr