Full list of all 23 Destiny 2 achievements worth 1,240 gamerscore. It takes around 80-100 hours to unlock all of the achievements in the base game on Xbox One.
The base game contains 13 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 10 achievements worth 240 Gamerscore.
Encounter an Agent of the Nine somewhere in the system.
Acquire each Hunter subclass.
Acquire each Warlock subclass.
Complete the "Light Reforged" quest.
Complete a Nightfall strike.
Collect 15 Red War exotic weapons or armor.
Complete 30 challenges.
Reach level 20.
Complete 5 Heroic Public Events.
Acquire each Titan subclass.
Complete a Heroic public event.
Complete a Nightfall strike on Master difficulty.
Complete a Nightfall strike on Grandmaster difficulty.
Complete a Triumph Seal.
Complete a Collections Badge.
Defeat a Forsaken Nightfall Boss.
Collect 10 Forsaken Exotic weapons or armor.
Collect 15 Forsaken Exotic weapons or pieces of armor.
Enter the Dreaming City.
Complete the "Shattered Throne" dungeon.
Win a Gambit match.
Earn 5,000 Triumph points.
Complete the "Last Wish" Raid.