Ann: Quarterly Activities Report and Appendix 4C, page-44

They do, but hardware is different. It sounds like they've got an automated testing system in place to quickly test a device (it could be something along the lines of playing their prerecorded cough and snore/breathing sounds to the device and comparing the results with their iPhone data).

They won't be able to feasibly test every single android device however, so maybe we'll see them advertise a list of supported devices (the most common devices). Or they might do some runtime calibration/testing (like what the iOS version of SleepCheck does to confirm the mic is working properly) to confirm the device will be capable.