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.
Acquire each Titan subclass.
Acquire each Hunter subclass.
Complete a Nightfall strike on Grandmaster difficulty.
Encounter an Agent of the Nine somewhere in the system.
Complete a Nightfall strike on Master difficulty.
Complete the "Light Reforged" quest.
Collect 15 Red War exotic weapons or armor.
Complete a Nightfall strike.
Complete 30 challenges.
Complete 5 Heroic Public Events.
Reach level 20.
Acquire each Warlock subclass.
Complete a Heroic public event.
Complete a Triumph Seal.
Collect 10 Forsaken Exotic weapons or armor.
Complete the "Last Wish" Raid.
Collect 15 Forsaken Exotic weapons or pieces of armor.
Defeat a Forsaken Nightfall Boss.
Enter the Dreaming City.
Complete the "Shattered Throne" dungeon.
Win a Gambit match.
Earn 5,000 Triumph points.
Complete a Collections Badge.