A local, professional display uses about 80lb of gunpowder (NEQ). When combusted this will produce about 40lb of CO2. To put this in context, most new internal combustion engines will produce about 190gm of CO2 per mile.
Therefore a single car would need to travel 88 miles to emit the equivalent amount of CO2 of your typical fireworks display. If you consider the a round trip distance for the entire audience to watch a single fireworks display, gunpowder is a fraction of the CO2 footprint.
Here is a map for New Years in Germany with a nice slider. Particle concentration increases up to 1000x the base-value of that day (which already includes people setting off fireworks earlier)
Unless it is normal for people at football games to ignite pyrotechniques, or they all smoke 5 packs of cigarettes each during the game, there is nothing that would make a comparable pollution.
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.
Now do the calculation that includes all of the direct suffering to humans, pets, and wild life, and then quantify all of the solid and liqueous waste associated with generation, transportation, and utilization, the latter including all of the waste associated with spectators attending the phenomenon.
What I think we'll all discover is that private transportation and the lack of robust recycling infrastructure and waste recovery the world over sucks. We should all do something about it.