Huawei just created new OS and removed all traces of Android and Linux. Just like that. If there is will, it is possible.
Can it run all of the kinds of apps that people (in the EU/US markets, which is relevant to the discussion at hand) actually want to run? SalifishOS doesn't even do that, at least not for me.
The will to create an OS is 0.0001% of the problem. There are tens of thousands of applications that people need to use that exist only for iPhone and Android.
There are dozens of functional mobile OSes. And OS isn’t useful unless it has application support for the tasks people want to accomplish, though.
...if there is will, a nice state sponsor and an already existing effective infrastructure.
Europe has none of the 3.
No, the phone variant of HarmonyOS runs on top of a Linux kernel.