If something can't be profitably made in the US then the only production for it will be explicitly for the government. And it will be a de facto monopoly and priced accordingly.
Maybe that's a tradeoff you're willing to make to make sure that there is always someone in the US who can make toilet seats. I would rather it be a more nuanced decision than a blanket mandate.
That said, I would also tax all imports to the point that the only imports worth buying are ones that are of a significantly higher quality than their domestic counterpart.
I would also ban trade with any countries that have awful labor and environmental practices. This one would be the most difficult, because how do you define awful? And how long do you keep the ban after they fix things? If you go back far enough the whole world gets banned.
Similarly todays Chinese laborers have no problems affording stuff they produce. Industrial production is very efficient, the products aren't super expensive even if you pay the laborers decent wages.
They are saying that there will be situations where the government has to buy some product domestically, but every private business and citizen imports that same product. The law would cause a domestic manufacturer to exist with the sole purpose of providing that product to the government. Since they won't have any other customers, or any competition, the price will be high.
Obviously the US can't/hasn't/won't out compete the entire world in all areas but it should be at least competitive.
Competition should extend beyond pure price. National values should be more than politicians talking points. If widget A is made by Uighur forced labor and widget B is made by a middle class labor in a free market, are you willing to spend more for B? How much more?
FWIW - I don't want a blanket mandate either but I don't think you have a convincing argument against it.