What's the difference compared to a phone with a radio firmware by a US company?

In both cases it's something closed and the government has shown overreach. (Yes, China a lot more than the US, but still ... things are not looking good a the moment. And I have no more trust, even if the political direction changes for a presidency period or two.)

But yes, ultimately we want open source firmware. Still, then there could be hardware backdoors anyways ...

I as a Canadian, lack trust too for the US these days.

And there are indeed issues.

Yet these issues are perhaps 1 foot high, and the issues with China and PRC's interference in domestic corporations, reaches to the moon.

There's literally no comparison. Even now.