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