@Doenyon the topic is about the physical dollar bills so I don't consider the credit card.
Well that's for sure people won't really want to accept the payment, but some stores have those signs they actually accept euro 💶 or something, so I believe it wouldn't be weird if the world that used to have dungeons dropping US dollars for 10 years already established something like "accepting payments in US dolars" at least in bigger stores like Intermarche (not your local store) but obviously it's much better to just exchange your money at the currency exchange point nearby, especially one where you can negotiate better rate if you want to exchange larger amount.
While handling foreign currencies you always have to keep in mind the exchange rate so that's nothing new.
Also people in Germany nearby the borders often go to Poland shopping so it's not weird when somebody asks to pay in euro there.