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