Full list of all 23 Destiny 2 achievements. It takes around 200 hours to unlock all of the achievements in the base game on Windows.
The base game contains 13 achievements, and there is 1 DLC pack containing 10 achievements.
Encounter an Agent of the Nine somewhere in the system.
Reach level 20.
Acquire each Titan subclass.
Acquire each Hunter subclass.
Acquire each Warlock subclass.
Complete Introduction: Crucible.
Complete a Flashpoint on Earth, Titan, Nessus, or Io.
Complete a Heroic public event.
Complete a Nightfall strike.
Collect 15 Red War exotic weapons or armor.
Complete 30 challenges.
Complete the Leviathan raid.
Complete the Leviathan raid on Prestige difficulty.
Complete the "Last Wish" Raid.
Defeat a Forsaken Nightfall Boss.
Complete a Triumph Seal.
Collect 10 Forsaken Exotic weapons or armor.
Complete a Forsaken Exotic Quest.
Win a Gambit match.
Enter the Dreaming City.
Pursue Uldren and the Fanatic to the Watchtower, and finish what you started.
Earn 5,000 Triumph points.
Complete a Collections Badge.