That'll confuse the average driver. The number of people that know the various measurements for fluids is not that high. I can totally see some future social media posts excited about the $2.99 price and then getting upset when the pump shows .25 gallons.
Even if you know the measurements it would be confusing to see a sign say $2.99 for gas and it turn out to be for a quart and not a gallon when you pull up. It's assumed at this point that it's per gallon.
"The United States switched to Metric to show smaller numbers at the pump", due to a surge in gas prices, caused by a war in the Middle East started for fabricated reasons, would be the most on-brand thing for America I can think of
In the previous 2022 gas price spike, some stations could not dispense more than $100 worth of gas since that would previously indicate something wrong with the station.