Offline streaming device creation

We need help in creating a device that, when triggered, transmits information to an App. However the device will be offline. It can not be by bluetooth, and wi-fi direct, it is an option but not the most viable, and it has a range of 12 meters, we need much more range. E.g. Garage gate that opens by sensor, which when opening transmits the information to an App, later created, however this sensor has no internet connection. Since it is not feasible to incorporate a hotspot for all sensors, of future customers.