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