Here is the full list of all 97 Divinity: Original Sin 2 achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Purge Rivellon of all Source
Complete the game in Explorer Mode
Complete the game in Classic Mode
Ascend to Divinity
Defeated the Kraken
Ifan: Kill Lucian
Gain entrance to Lucian's Crypt without following the Path of Blood
Defeat Adramahlihk
Rescue Arhu
Obtain Anathema
Discover Reimond's Lair
The Red Prince: Kill the Red Princess
Get caught breaking the law
Arrive at Arx
Enter The Arena of the One
Convince Alexandar to ally with you
Enter the Academy
Arrive at the Nameless Isle
Learn of the Council of Seven's location from a higher power
Become champion of the Driftwood Arena
Receive Dorotya's kiss
Learn of the Council of Seven's location from The Advocate
Take the ferry to Bloodmoon Island
Unlock your third Source Point slot
Perform successful surgery on Natalie
Kill Andras, the necromantic dog
Correctly answer all of Crispin's questions
Unlock your second Source Point slot
Escort Saheila outside without fighting the Lone Wolves
Equip runes to all of an item's available slots
Adopt Peeper
Help free Mari from the Voidwoken
Speak to an animal's spirit
Welcome Tarquin to the Seekers' service
Kill Radeka
Become champion of the Fort Joy arena
Meet Meistr Siva
Arrive at Reaper's Coast
Enter the Hall of Echoes
Escape Dallis' siege on the Lady Vengeance without killing every minion
Take command of the Lady Vengeance
Use your first Source Skill
Defeat Alexandar in Fort Joy
Face a higher power
Remove your Source Collar
Arrive at the Sanctuary of Amadia
Rescue Gareth from Braccus' Armoury
Escort the Black Cat out of Fort Joy
Flee Fort Joy for good
Escape the kraken's clutches
Gain the Hero tag
Win a persuasion event
Arrive at Reaper's Eye
Perform a successful theft
Force Dallis to retreat from combat in Fort Joy
Kill Slane
Escape Dallis' siege on the Lady Vengeance after killing every minion
Set Gareth on a path of vengeance
Set Gareth on a path of reconciliation
Learn of the Council of Seven's location from Malady
Awaken the corrupted Ancestor Tree on Bloodmoon Island
Lockpick your way into Mordus' hidden lair
Tame Featherfall
Destroy every Voidwoken egg in Reaper's Cove
Serve Garvan the tainted stew
Pray at every altar on the Nameless Isle
Convince all party members to let you ascend
Discover the hidden entrance to the Academy
Swear to the Covenant
Successfully walk the Path of Blood
Share Source with all of Rivellon
Submit to the God King
Share Divinity with The Doctor
The Red Prince: Become the father of dragons
Lohse: Embrace your demon
Lohse: Banish your demon
Sebille: Serve the Mother Tree
Sebille: Destroy the Mother Tree
Fane: Return the Eternals to Rivellon
Fane: Embrace this strange new world
Ifan: Forgive Lucian
Beast: Assassinate the Queen
Persuade Toyseller Sanders to give you his amulet
Make a deal with Adramahlihk
Beast: Ally with the Queen
Shapeshift into every race
Complete the game in Tactician Mode
Craft a scroll
Kill an enemy using Teleportation
Craft a skill
Use the Curse skill
Gain the Villain tag
Craft a grenade
Successfully begin a match in Arena Mode
Successfully begin a Game Master session
Complete the game in Honour Mode
Sebille: Kill the Master