The Trump administration is banking on the idea that it is easier for the rest of the world to replace what China makes than for the rest of the world to replace what the US makes - e.g. rare earth mines and refineries can be stood up (at cost) for the industries that need them, but US software (which would include Windows, Google Search, Android, iOS, hardware device drivers, etc.) will be much harder to replace. Countries would be told that, if they want continued access to any US software, they would need to cut China off from trade.
This is probably the greatest leverage the US actually does have, since its software ecosystem does dominate the world. I've mentioned this many times before - the US is a financial and software super power. Google Search and Microsoft Bing controls about 95% of ALL global search. Similarly for operating systems like iOS and Android. It is the one industry where US dominance is at the level of Chinese dominance in rare earths, so it makes perfect sense for Trump to use it as leverage in the extra-territorial sanctions game.
But of course, just like with China and rare earths, you get to play this card only once. Once you play it, the resultant economic devastation will set off a trend of "de-risking" from US software that could permanently cripple its dominance. What's more, the software industry makes up a MUCH larger share of the US economy than rare earths does the Chinese economy, so the financial impact to the US could be devastating.
The real question, though, is how much the rest of the world stands to gain from siding with the US vs. China. The intimidation tactic here is essentially a bluff: if the Global South falls in line with the US then this move would be equivalent to the US telling the rest of the world "you can't trade with China" and them saying "okay." China would be isolated and that could cause severe consequences for its living standards and industrial development, as what would follow soon after - if the US got the Global South to agree - is probably a resources embargo (iron ore, minerals, food, etc.) It'd be like turning into North Korea.
But that's why it's a bluff. The US wants China to fear this outcome, but there isn't confidence that the Global South will actually follow through. If the alternative happens, where the Global South decides that it'd rather just replace US software, or operate separate software ecosystems, then it's the US and its close allies that will become North Korea. This is why it is the nuclear option. Once it is out, there is no coming back.