FFXIV used to have something like this - until Stormblood when SE decided to change their payment model. Prior to Stormblood people in Barzil were able to pay in their local currency, with 4.0 they changed it to USD. Back then they offered refunds for everyone who purchased Stormblood but couldnt (or didnt want to) keep playing due to the price basically tripling. Back then they argued they made the chance because it was unfair that some people paid less than others (I'm not saying that that was a good argument or even their real reason, though...)

Considering that history, I think its unlikely that they'll adjust payment for countries like Brazil again - so Steamwallet might be your best option.