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