Version 2, equipped with an ESP8266 (around $2) is now offering a webApp to read the status and adjust the settings.
It's still a prototype, the hardware is not yet upgraded and will likely need a new PCB, the software is in branch Wifi of the github project.
Here is how it looks like for now (with setting displayed, one setting being edited):
Next improvement will be periodical recording of measures on an external web server to provide graphs showing the evolution.
Several devices sharing a GSM module through Wifi (Or/and bluetooth if I manage to get an ESP8232 to work :)) will be available in version 3.