Petrodollar hypothesis is debunked. The total volume of petrodollar trade approximates minutes in stock markets. This simply isn’t a real factor anymore; a lot of people think it is because there are writings from the 70s that are compelling.

As you said, trade volume doesn't drive valuation, it's reserve size.

Which goes up with inflation btw, so you can export inflation. Actors who maintain reserves of your currency will have to keep buying more from you, providing you with benefits.