they’ll also support Motorola.

Motorola (the company whose name and reputation has been well known for decades) no longer exists. Its successor is called Motorola Solutions, and it's not the company making the upcoming GrapheneOS phone. That device is coming from Motorola Mobility, which is a completely separate company, owned by China's Lenovo.

thus making me wonder whether the Chinese government can affect it

They absolutely can. And, since they have the means, the incentive, and no reason to fear repercussions, they probably will. The questions on my mind are how they will affect it, and who will find out.

I hope the hardware and firmware features used by GrapheneOS will become common some day. I think Sony's Xperia line comes close. Perhaps the GrapheneOS maintainers should talk with them next.