The MySense app uses your smartphone camera to scan the QR code only. MySense uses your location and Bluetooth to onboard the devices. Note that access to the Bluetooth settings is only asked when installing these devices. Therefore, if your home hub or sleep sensor goes offline, you will need to allow MySense access in order to repair it.
Permissions to access things on your phone or mobile device are limited to only times where the MySense app is active and only used when pairing devices or the initial installs. These settings may be turned off after a successful setup but it is advised to keep them active to help diagnose or repair any technical issues that you may face.