curl --request GET \
  --url https://discord.com/api/v10/applications/{application_id}/activity-instances/{instance_id} \
  --header 'Authorization: <api-key>'

{
  "application_id": "<string>",
  "instance_id": "<string>",
  "launch_id": "<string>",
  "location": {
    "id": "<string>",
    "kind": "gc",
    "channel_id": "<string>",
    "guild_id": "<string>"
  },
  "users": [
    "<string>"
  ]
}