I wonder if this would be a possible use case for the stupid Dyson headphone filter. It uses positive pressure to provide you with filtered air. However, I'm not certain the filter would be enough to clean exhaust fumes.
Another issue would be that you probably shouldn't be wearing headphones while biking, but maybe they have a passthrough mode.
From the reviews I've seen of it, the Dyson headphones wouldn't help. I think it was MKBHD that specifically was testing to see if they would block out exhaust fumes and they were next to useless.