Expertise exists primarily where things primarily happen. If no companies manufacture complicated products in a particular country that doesn't mean the country is too dumb to make it, it means they don't have a large pool of experts in that field.

If you read the article, the founder of purism even says as much.

"After we were successful on the Librem 5 crowdfunding campaign, we took our own electronics engineers (EEs), and then we worked with Chinese design and manufacturing through 2018, 2019, and 2020, because that's where every phone is made."

So the only phone that qualifies for "Made in the USA" tag learned (at least in part) how to make it from Chinese engineer(ing firm)s.

So basically you can find qualified workers everywhere. There's a valid question about the cost. But to say the problem is lacking "skilled workers" is laughable as most of these skills are machine dependent and can only be learned on the job after the factory is built.

Are there skills involved with building such factories and production lines? Where do those people get their experience?

American and multi-national companies often build such factories in low-income countries. It's not that no one in the US knows how to build factories. It's purely a cost/regulation question.

The skills to live on $1-$2/hour apparently.

He's not saying americans couldn't learn to do it. He's saying there aren't many people in the US to hire who already know how to do it.

One particularly bizarre delusion that some people suffer under is to assume that everything they don't know how to do is easy.

It's the same kind of people who would design a city with no toilets or waste water treatment. Everything is easy when you ignore half of the requirements.