To quote Pitch Meeting:

This is the world’s most expensive TV show, we can’t help it if the audience hasn’t watched the last episode.

Seriously tho, Fury was in space because Thanos scared the shit out of him and with Tony gone they need some sort of planetary defense.

As for the Avengers… what Avengers? Tony, Natasha, and Cap are gone. Bruce and Clint are disabled. Thor is off-world. No one knows how to contact Spider-man. Ant-man and the Wasp perhaps? (I’m still choked they aren’t trapped in the Quantum Realm like that script originally called for.) I will give you Dr. Strange tho… he should absolutely be helping out.