Again looking at the map of Germany as well as the article from the BBC stating an increase of Microplastic by over 1000% compared to the baseline shows that fireworks are a very strong additional pollutant.

People in the US drive their cars all the time. During rush hour more cars are emitting in traffic jams than are driving to a football match. Yet we see these huge spikes in pollution when there is fireworks.

Think about it: Everything form a firewokr that does not turn into CO2 will stay dispersed in the air or fall down as debris. This is most of it, as the op pointed out himself the GHGs to be only a small part. Meanwhile for cars the vast vast vast majority of its emissions in quantitative terms are CO2 emissions, with particles, NOX and Microplastics being much less. They also pose a massive problem, but because of hundreds of millions of cars on the road every day.