IoT SOS Device Development

I’m building a compact SOS gadget that pairs with a smartphone over Bluetooth and I need someone who can turn the idea into a working prototype and production-ready design.

Core functions
• When the user presses a single hardware button the device must immediately:
– fetch or relay the user’s location,
– push an emergency alert message, and
– trigger the phone to place a voice call to a preset number (or 112/911) through Bluetooth.

Connectivity & ecosystem
Everything has to run entirely over Bluetooth (BLE). Wi-Fi or cellular support is not in scope right now, but please architect the firmware so those radios could be added later without a rewrite. The companion app should work on both iOS and Android, sharing as much code as practical.

What I expect to receive
• fully commented firmware for the chosen BLE/GPS-capable microcontroller
• a tested schematic + BOM that can be sent straight to a PCB fab/assembly house
• cross-platform mobile app (React Native, Flutter or similar) that:
– handles pairing, location relay and alert configuration
– runs in the background and auto-dials when the device requests it
• build/run instructions and short video demo showing the end-to-end flow

Acceptance check
The button press must reach my phone and complete a call to my chosen number in ≤3 seconds in a normal urban environment; GPS location and an SMS/notification must appear simultaneously.

If this sounds like your wheelhouse, tell me which chip set and app framework you would start with and any past project that proves you can hit the three-second target.