Well thought out. Excellent work. Thank you for making this available as open source!
Side note -- I wonder if it's possible to have a companion system to scan regularly for the signal at home for the elderly. Then notify caregivers from the companion using available wifi/cell if the SOS is detected. Since it's so well behaved it seems like even having a regular wellness check mode would be possible. Having a companion system for relay would allow the app itself to never need WiFi/cell and have independent care notifications protocols that wouldn't need to be maintained in the app.
