And the radio firmware.

From a phone by a Chinese company.

Unless GrapheneOS handles the radio firmware, not really interested.

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 ...

They address this issue specifically (don't have the links now, I'm sorry) - basically one of the "must haves" for the hardware to be considered good enough (meaning pixels have it and new motos will have it) is a hardware capability of the strict separation between the os and devices, ie baseband unable to influence the os (snoop/inject stuff, etc).

Don't remember that at the moment, it should be one of the requirements they list under "future hardware" In the FAQ.

I dont think grapheneos handles radio firmware on pixels, radios also not made in the US. I wonder if even apple does, as their radios are also not made in US.