Is it possible to use this device with Bluetooth only – logging data on an Android or iPhone ?

The SwitchBot indoor and outdoor thermometer and hygrometer is a Bluetooth product, compatible with both Android and iOS systems. You can certainly use only the Bluetooth function of this product. You can view or export data through your phone within the Bluetooth range (120m, unobstructed). The on-board storage days for the SwitchBot outdoor temperature and humidity sensor is 68 days, which means you need to transfer the data to your phone every 68 days and cache the data within two years in the phone app.