So that's still from half a decade ago. Again, it's not impossible that US and Israel could find vulnerabilities in devices built on an independent stack, but at least it's not part of the design there. And that means these vulnerabilities get fixed over time. Your support matrix from 2024 does not show a single Chinese made device which proves my point. It's US based tech stacks that are compromised.
The point I'm making is this. One tech stack might have vulnerabilities due to negligence and human error, the other has backdoors baked in by design.
Just because something is a SoC or not is not really relevant. That's just a type of architecture. What matters is if the specific implementation is compromised or not. I'm not aware of any evidence that recent Chinese devices are compromised. However, your own link shows that iphones are.
You're right that chips alone aren't the deciding factor, but they are the core of the stack, and if your hardware is compromised then it really doesn't matter what your software is doing at that point.
While there might be a case for graphene being the most secure software stack, the hardware could still betray you and there's little graphene could do about that. Meanwhile, there is zero evidence for the claim that latest ios or maybe a pixel with the latest android are preferable to HarmonyOS or HyperOS. If anything, you yourself just showed that iOS should not be trusted.