That's exactly how it works. You can't make smartphones with magic pixie dust. You still need rare Earth materials, and they ain't coming from the U.S. China has Africa on lock so it's going to come from them. All Apple/Google has to do is tell China don't partner with Musk.
SpaceX was already working on a satellite smartphone with T Mobile, even before Musk took over Twitter.
That's more for commercial or governmental operations. It's not for us plebes.
As for contractors to make a smartphone, they are a dime a dozen and not just in China.
US taxes and regulations say otherwise.
Smartphones are made in India, Korea and other Asian countries as well.
Over 90% of all smartphones are made in Taiwan or China. If they're made in India, it's probably the flip phones from the late 90s.