I wrote "the one you can always settle your debts in (though that's not universal)" to say that this may be so in some jurisdictions, maybe the US, but I'm not from the US. All I know is that if I make a contract in USD or Zloty or Yuan (or any other foreign currency), the contract is in that, deliberately, and a local court here would not make me pay in local currency. I picked the other one for a reason.

I know it say "for all debts" on USD bills, but if a US company deliberately made a contract to import something in another currency, could the court say no? though it's the US, it might think the USD is automatic world currency, like it goes around thinking US law is world law. Wouldn't surprise me, but then, that would be empire bs.