An industry insider speculates that Huawei will release a HarmonyOS-powered smartphone in late 2020. It will reportedly be a low-cost 5G-ready smartphone exclusive to the Chinese market. Huawei is expected to tell us more about its plans with HarmonyOS at its developer conference this September.
https://www.notebookcheck.net/Huawei-likely-to-release-a-smartphone-running-HarmonyOS-later-this-year.488926.0.html
I'm going to say it. Making OS is far more difficult to make than making apps. China already had problems with in-app security, I can't seem to think this will be any different. If Windows failed in mobile market, this will too. Android and iOS won't be threatened.
I believe hardly anybody is actually "convinced" by 5G as it is, however China's carriers have the greatest freedom as well as political pressure to push 5G at all costs, so throttling 4G and reallocating 4G bands for a so-called upgrade to 5G at the same bandwidth could "convince" more users to pay up.