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