We already have nearly full employment, too. Unemployment in the US is low by global standards, typically 4% or less. We don't have a systematic problem in America with people not being able to find jobs. In fact, ESPECIALLY in manufacturing, we have more jobs than people to fill them, and the manufacturing goes undone--high labor costs being a key reason the jobs left the country in the first place. The whole idea that the current America even need these manufacturing jobs is false. Americans have enough higher-value jobs that the manufacturing jobs go unfilled, then they move overseas where there are people to do them.
So even if lots of manufacturing jobs "came back" somehow, the only way they would be filled would be
1) import the workers with them. This is actually a very "American" model. Bring on the factories, and bring on the immigrants to work them. Everyone would benefit, including current Americans. But that would require letting go of scarcity mentality and acknowledging that immigration is a good thing. This is effectively what happened for existing manufacturing on-shoring projects, by the way, although it's not widely advertised because it doesn't mesh with the optics of the administration: a large fraction of workers at TSMC in Arizona are actually Taiwanese. And that shouldn't be a scandal; why should it? Build a factory, and import a skilled workforce at the same time. Assimilate those immigrants as citizens, and you fortify both your capital stock AND your human capital stock. This is what made America great; what could be more natural? But following this movement en masse and for lower-value manufacturing would also require America to let go of other scarcity mentalities and redevelop ability to build infrastructure like transportation and housing, which America has completely lost...we can't even build housing or transportation for our own children. No wonder people don't support more immigrants, when their own children are facing spending 4X more for an old shack shared with others, with a crushing commute to work...and remember we are talking about low-value manufacturing jobs, like assembling iPhones, so most of that work must be done at the factory and not remotely. This is why my company's main factory in Japan has its own train station. But in America, we don't even have the train, and we can't even build one. Look what happened to the housing market in Canada for an example of what happens when you allow even modest immigration, but allow zero housing construction. America, without something like a major Georgist prosperity revival movement, cannot grow. And this administration is NOT a Georgist prosperity revival movement; it's peak scarcity scrambling-for-pieces-of-the-pie-and-trying-to-negotiate-more-at-the-expense-of-others.
The other way to fill the proposed low-value manufacturing jobs like iPhone assembly, demonstrably the one that's being pursued, is 2) requires the manufacturing jobs to pay more, AND be better jobs, than the current jobs available in America. And you can ask anyone who works in manufacturing, even when manufacturing jobs pay well, they aren't what modern Americans consider "good jobs", which is why the manufacturing in America is higher-value capital-intensive manufacturing done with machines. Even if you could make as much sitting on an assembly line assembling iPhone screens as you could with your hybrid-schedule laptop-job, you would still not take that job because it's worse. This is basically the status quo that caused the low-value manufacturing jobs to leave in the first place...we basically don't need them because we have other, better jobs that drive up wages. Which is supposed to be a GOOD THING that means your economy is strong and prosperous.
This administration is constantly trying to square impossible circles: Bring manufacturing back, but do it with policies (tariffs) that make manufacturing in the US EVEN MORE expensive than it was before, which is the whole reason the jobs left in the first place. Reduce our trade deficits, but do it without weakening American hegemony, when American hegemony is the whole reason for the trade deficits in the first place. It is all 0-braincell tilting at windmills. There are paths to bringing manufacturing back to America, because we know why manufacturing left America, but you can't actually bring manufacturing back to America but not... actually bring manufacturing back to America.