https://www.reuters.com/article/us-huawei-tech-developer/huawei-unveils-harmony-operating-system-but-wont-ditch-android-for-smartphones-idUSKCN1UZ0MH >Huawei Technologies unveiled on Friday its proprietary operating system for smartphones and other devices, as U.S. trade restrictions imposed in May threaten to cut the Chinese firm's access to U.S. technologies such as Android.