It's a good sign that Purism can do this at all, even though it's a boutique/fringe product right now.
Note that it's $1,999+ for mostly made/assembled in USA version, vs. $999 for Purism's made in China version.
And China is more capable at scaling, if the product were ever competing on price rather than principle. So still a ways to go to be competitive at manufacturing.
It's definitely more expensive to produce in the US, but I think it's priced at $2000 because this is literally the only option for people who want/need a US-made phone. I don't think it actually costs them double to produce.
I am actually surprised it only costs double. Have you compared wages in china vs US? They went a lot higher in china by now but are still way below.
Definitely possible, this one is mostly US-built: https://puri.sm/products/librem-5-usa/