> Though if a company is selling both to the US
and to somewhere else that doesn't use the dollar, the cost increase may end up damaging business elsewhere.
Unless the "somewhere else" uses the yuan, currency devaluation doesn't work that way. Even if the exchange rate is tied to the dollar by fiat, devaluing it does so against all other currencies, because nobody is going to accept less yuan for their euros than they could get by exchanging euros for dollars and then dollars for yuan.
But that still doesn't mean they can raise prices, because the whole point of the currency devaluation is to make them more competitive. Raising prices does the opposite. And you can't claim the whole thing as margin if that would have caused you to lose the contract to begin with, which was the original reason for the currency devaluation. You may also have to compete with other local suppliers who are operating under the same nominal reduction in local costs.