Besides, Fury probably didn’t waste any time reestablishing his spy network once he was in the land of the living again, making for a better use of his time.
In any case, Christopher Markus and his writing partner Stephen McFeeley always planned on Nick Fury sitting on the sidelines during Avengers: Endgame’s third act, and with all the characters involved in that battle, I doubt there was anyone in the audience thinking, “Hey, where’s Fury?”