Let's face it, from what we've seen so far, Destiny 2 is not the most demanding game out there when it comes to graphics.
For single-player, a mid-range GPU will have you more than covered at 1080p using high quality settings and many cards will even provide a smooth 60fps at 1440p. AMD's GPUs lag behind quite a bit at 1080p but come alive at 1440p and 4K where they were very competitive.