It is a good thing to get a heads-up on Mass Effect Andromeda before it is available on the market. There are certain missions that players need to do like the Nexus Reunion. However, they do not need to be shocked because the party is quite different on what they are expecting since the place is almost deserted.
To start the Nexus Reunion in Mass Effect Andromeda, they need to go to Nexus. According to VG247, when the players arrive on the ship, they will be surprised on the current situation of Andromeda. However, although some side quests will be available while they are onboard their main goal is to set-up a different reunion in the ship. Ryder and his company will have to talk to an AI that will will tell them to leave the place since there is nothing there for them. After that conversation, they must talk to the maintenance man to be informed that Hyperion is lost.
As per USGamer, somewhere along the Nexus, they will meet Kandros. He will point the Pathfinder team to Director Tann, the leader of the Andromeda Initiative and Foster Addison, responsible for Colonial Affairs. After they are done talking to them, they will be instructed to complete the First Strike mission.
It means that the Nexus Reunion will only be finished when they are done with the First Strike mission in Mass Effect Andromeda. The Pathfinder team must head to Militia to ask Kandros what they can do about the Strike Team.
However, the sidequest in Nexus Reunion is not about fighting intergalactic forces but they need to converse with the Strike Team online. Once, they are done with the First Strike, it will be indicated that the Nexus Reunion is over and they can now complete other bigger side quests in Mass Effect Andromeda.