Apparently not. You need their app to set the device up (i.e. connect the device to the WiFi, and pair the bluetooth sensor(s) to the device).
The app only communicates with the Sense device via bluetooth when setting up its WiFi connection, everything else goes through a web API to the company's servers.
I haven't tried, but now I wonder if the alarm even works without an internet connection.
I don't believe so. Alarms etc are (I suspect) stored locally, but to enact a change on the device I believe it has to send it upstream via the phone app and the device then retrieves the changes.
So when the service is shut down my expectation is that I won't be able to change any of my device settings. Not to mention that the room data and sleep data will be unavailable.
This is the exact reason I don't really like cloud connected IoT devices. For instance, while I'd love to have a Nest thermostat, I refuse to us it due to requiring a connection to function fully. So I've opted instead for a 'dumb' thermostat with WiFi and an open and well-documented local API. About the only current exception to that in my house is my Amazon Echo, and that will be replaced as soon as someone comes out with a viable local-only alternative.
Yeah, I agree. I will always give preference for devices that fully function without internet access. For instance, the Venstar thermostat I use has a cloud component where you can track stats and remote control the device if you want, but it's 100% optional and the device loses no functionality, beyond the on-device weather, when there is no internet access. The local APIs allow me to easily integrate it with my HA controllers as well.
The app only communicates with the Sense device via bluetooth when setting up its WiFi connection, everything else goes through a web API to the company's servers.
I haven't tried, but now I wonder if the alarm even works without an internet connection.