Where do you think this originates from?
China ships a rather large amount of stuff to these countries to take advantage of the trade agreements. So much that you can find satellite images of large yards in Mexico that are used for this purpose with barely any effort.
These takes are much more doomer than I'm willing to bet the supporters of "bring everything back" realize. Do you have no faith in the US economy / populace adapting to a hypothetical all out war with China?
It’s not like WWII where you have a majority population that works on the farm or in a factory with their hands, and at home fixing stuff that breaks. That sort of population can be rapidly redeployed. We would need to start from the basics like “how to turn a screwdriver” for a huge portion of the workforce.
When you really start looking into things, nearly everything points back to China at some point. Pharmaceuticals? The APIs or at least important precursors largely originate there - even if they hit a middleman country first. Then you get into basic components and it’s the same story. That part from India or Mexico might not be available without China as a backstop.
It’s not an impossible problem, but it’s a problem that took decades and a generation or two to destroy. It’s far easier and quicker to destroy things than build them.