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