We have a ton of questions ahead of the film’s release, and the limited footage doesn’t answer much.
The marketing campaign for Avengers: Endgame has been purposefully vague, mostly setting up the bleak world after Thanos’ finger snap of death (aka The Decimation).
So if the fandom actively tries to avoid spoilers, they should hopefully be able to see Endgame without knowing anything about the film’s contents.
While the surviving heroes will attempt to unite the stones and reverse Thanos’ mass extermination, it’s unclear exactly how.