I guess this is a cool idea, at first I thought don't we already have plenty of options that's already been well established as tried and true for decades? However, everyone already has a smartphone on their person at all times, so incorporating an app in the phone for when the grid is down to work with existing ota radio communications sounds like a good idea
New system aims to keep people connected when networks fail
https://www.helpnetsecurity.com/2025/10/08/off-grid-emergency-communication/
"When disaster strikes, communication often fails. Cell towers can go offline, internet connections can disappear, and people are left without a way to share information or ask for help. A new research project ... .. developed a system that combines low-power radios with a smartphone app. It is designed for situations where traditional infrastructure is damaged or taken down, such as during natural disasters or large cyberattacks.
The project uses LoRa, a long-range, low-power radio technology, .... The researchers built a smartphone app that links to the radios through Bluetooth, allowing civilians to send messages and share location data using familiar tools on their phones. ... . They compared two frequencies, 868 MHz and 433 MHz, and two types of LoRa channel settings. The best results came from the 868 MHz .. This means messages were delivered reliably across a dense city environment..."
https://www.helpnetsecurity.com/2025/10/08/off-grid-emergency-communication/