If there's no open flame in the oven there are coconut husk brushes that are probably safer than metal wire brushes.
I guess it could work to get most of the burnt flour into one spot and then vacuum it out?
New Haven style pizza kinda embraces leaving that stuff in the oven. In the videos of them in operation at least one of those places is pulling pizzas out of the oven and then launching them on to what seriously looks like a coconut husk door mat on a counter, and then pulling it back off of that before cutting and serving. Clearly done to remove excess "char".