If Aliens showed up to earth to trade cheap stuff and energy from their star trek replicators, I'm pretty sure the US oligarchs would ensure a rulership that goes to war with, or at least install prohibitive tariffs on, the Aliens instead, to protect their profits. China offers a similar role.

We could have full employment if we just get rid of wires and pipes that go to homes. Hire people to go get you firewood and water from the river, and throw your waste into the street. This does result in a subsaharan economy, and cannibalism, but everyone is structurally guaranteed work.

If instead you import from China/Aliens, you are rich in stuff. Still plenty of work available in construction and selling stuff, and UBI is a path to keep the "country" rich, primarily in being a desirable place to live in freedom.

Even in the unlikely event of US reindustrializing to become an uncompetitive economic island to rest of the world, it would result in a relatively declining standard of living, and no exports, compared to those trading with the Aliens.