I don't think you can drive people away from the US dollar, simply because any such destabilising action will hit the real economy first. And the US has seen low consumer inflation for years now.

MMT absolutely does take account of forex by recognising that a government has a large amount of power to dictate money flows within the country, but very little power to compel terms of trade overseas. And most countries need to continuously import certain things which cannot be substituted locally, especially fuel.

Expanding the money supply lets people buy more locally produced stuff, but not more imports. This even scales down to local token currencies ("Bristol pound") or Krugman's "babysitting tokens" thought example.