For devices such as the Motorola Edge plus 2023 (US) and the Motorola Edge 40 pro (international) deployment of the Snapdragon Spaces Services and Spaces Samples for Unity and Unreal Engine is not possible at this moment. 

Therefore, the optional step for registering the device's serial number as recommended on the https://docs.spaces.qualcomm.com/platform/setup/lenovo-thinkreality-a3-dev-kit#optional-step-10-serial-number-registrationwill not have an effect for now. 

As a workaround sideloading Snapdragon Spaces Services and Samples is available via adb. Instructions for sideloading the Snapdragon Spaces Services are available in the https://docs.spaces.qualcomm.com/platform/setup/launching-apps-on-lenovo-thinkreality-a3-dev-kit.