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