I Am Here
After NWH Peter started learning the Mystic arts, because of society and reality collapsing, and is trying to find a way to fix everything. He finds a close enough spell and remakes it to the specifications he needs. This spell lets him bodily travel to a point in past of great personal grief.
He takes the stones from Tony and snaps, appearing in the arc reactor explosion along with Morgan and Vision. Other chosen people only get their memories and sometimes some positive extra character development. They all have their powers.
Wanda blows up the HYDRA base and a few others, convinces Pietro that Tony wasn't at fault for their parents' death and mobilizes Bucky, Sam, Scott (who's already started the theoretical training for Cassie) and Yelena. She calls Tony's secretary and asks for a call to him, and when he calls her back, she asks if he's here, saying that she already got a few others that are here (aka back from the future).
Clint is devastated that Natasha is not here (spoilers: she just needs a little time).
Carol has just finished a mission, when her ally comments on the crazy energy sensor data, which points to a cosmic energy discharge in a backwaters corner of the galaxy that still has shockwaves and stuff, and she sees where it is and freaks out, and shoots off, throwing over her shoulder that her home is in trouble.
Thor and Loki are sparring and lose concentration. Thor accidentally injures Loki and freaks out, begging him to live.
Everyone gets together and destroy Thanos, and scatter the stones in better hiding places and ward them.