In the latest video on the Tech Minds YouTube channel Matt tests out the Meshtastic software running on varius Lilygo LoRa devices. Meshtastic is software that can run on cheap LoRa hardware that enables off-grid mesh network based communications.
Being mesh network based means that there are no central repeaters, and instead each device can extend the range of the network by being a repeater itself. Meshtastic can run on various cheap 'Lilygo' branded LoRa devices that come in 433, 868 or 915 MHz license free frequencies depending on your regional band plan.
In his video Matt tests out various models in the Lilygo range, including a ESP32 based wrist watch and he also shows how to install the firmware on each using the online flasher.
Source: https://www.rtl-sdr.com/tech-minds-test ... a-devices/