In an ideal world, we'd get employees from the ranks of the under-employed: gig workers, Uber drivers, people working multiple part-time jobs.

That would create a shortage in the labor market in those areas, but we'd find ways to adapt: automation, public transportation, etc. There could be a net gain, where the new manufacturing products produce more net income, and we'd be able to afford better conditions for the remaining Uber drivers etc.

And yeah, maybe some people would avoid becoming homeless drug addicts if they had a reliable manufacturing job available.

Or... not. It seems wildly unlikely that we'll build a whole bunch of factories that depend on a wildly erratic tariff schedule. And even if they do, the circumstances don't seem likely to produce "reliable manufacturing jobs" when those jobs left the US a long time ago precisely because people didn't want to pay for them.