What exactly it is, Smith is keeping coy. Presumably, this is to allow players to discover this special something when Destiny 2 launches on September 6:
There’s only one qualifier to being able to experience whatever this fan recognition ends up being—players will need to buy and play Destiny 2 on the same platform where they played Destiny 1. In other words, someone who played Destiny 1 on PS4 will have to be using the same PSN account for Destiny 2 to recognize the history of playing the first game. In the same way, those who have played on Xbox One will need to still be playing on Xbox One.
If fans have purchased a new console or upgraded to a PS4 Pro or Xbox One X, for example, they will still experience it as long as they use the same PSN or Xbox Live account. That does mean, however, that this secret fan service will not exist on PC, since Destiny 2 will be the franchise’s maiden voyage on that platform.
Keep an eye open when the game comes out next week for this special surprise that Bungie has in store for fans who played Destiny 1.
Destiny 2 releases on September 6, 2017 for PS4 and Xbox One, and on October 24, 2017 for PC.
Source: Wired – YouTube