If you're sincerely interested in the answer to that question, I'd highly recommend reading the article, because a good portion is dedicated specifically to answering that.
I read the article - up to a point. The guy goes to such great lengths not to admit that a huge proportion of the physical parts in the phone are from China. E.g, he keeps saying "Western distributor" to avoid saying "China-made." (Think about it: why would any reader care about the distributor's nationality?!) He just rambles on and on, trying to baffle us with bullshit - eventually I stopped reading.
There is zero chance that a smartphone will ever be made out of 100% US-manufactured parts, or even close to it. And the evidence is right in this article, if this is the best effort to manufacture a "US phone."
If you're sincerely interested in the answer to that question, I'd highly recommend reading the article, because a good portion is dedicated specifically to answering that.