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