We don't have to eliminate all transmission to stop Covid, we just need to bring the R value below 1 and keep it there. I don't think that direct transmission via sneezing is a significant cause of spread, but sneezed particles could remain in the air for a long time, long enough for a filter to make a difference.

I don't think there's any uncertainty left in airborne transmission: https://www.forbes.com/sites/jvchamary/2021/05/04/who-corona...