I get what you mean and it's a fair point. But I would still go with Meta as the most immediate threat in a war with the US.

As the ignorant I am, my understanding is that the phone manufacturer has a level of control on the way Android works and so it wouldn't be as easy for Google to access any individual Samsung or Xiaomi phone as it is for Meta with WhatsApp, an app they fully control with permissions to use (way too many) phone features regardless of brand.

Plus, getting both Google and Apple to cooperate and coordinate sounds harder to me than just going to one company, that is basically controlled by only one person.

They are probably using Xiaomi which is based in China, using AOSP with whatever mods they throw on it, which isn't based anywhere and is open source, or it could be Huawei too.