There are currently more than 900 million devices that run on HarmonyOS, with more than 2.5 million developers creating apps for Huawei’s mobile platform.
The last time I looked into HarmonyOS, it was an intentionally vague umbrella name for a family of operating systems and kernels. On phones and tablets, HarmonyOS was a fork of Android 10 (this was when 13 was new). On embedded devices, it was a Linux kernel fork. There were supposedly some unifying features and APIs between them, but the documentation felt very much like Huawei didn't actually want you to know what HarmonyOS is.
It'll take some time, but seems like they're well on their way. Things will start getting really interesting as Huawei starts gaining more ground in other countries outside the west. We're likely going to see a tech split between the west and the rest in the coming future.