Here is the full list of all 57 Psychonauts 2 achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Crack all Vaults
Acquire all Upgrades
Find all Figments
Tag all Emotional Baggage
Achieve Rank 100
Purchase all Pins
Completely fill your Astral Wallet
Return to where it all started
Scavenge all MISSION CRITICAL PSYCHONAUTS ASSETS
Dissolve the Deluge of Grulovia
Recover your mental energy with a Dream Fluff
Frequent Fatherland Follies
Break all 3 Gramaphones in Fatherland Follies
Soothe Lucrecia's Lament
Peruse Cassie's Collection
Empty Bob's Bottles
Discover the Astralathe
Raid the Tomb of the Sharkophagus
Deliver Cruller's Correspondence
Repair Ford Fractured
Purchase all Otto Shot Filters
Complete Queepie Quest
Treat Ford's Follicles
Bowl Strike City
Achieve Rank 50
Plate Compton's Cookoff
Throw a Regret's anvil at another enemy
Throw a Judge's gavel back at him
Complete Lili's Request
Max out your Dream Fluff capacity
Max out your PSI Pop capacity
Help Dion Setup Aquatodome
Complete PSI King's Sensorium
Find the real Panic Attack during his Phantom attack
Tune in to a Stray Thought
Take a photo with the Otto Shot
Complete Gisu's Psychoseismometer Quest
Upgrade to the Astral Wallet
Find the Family Camp
Pyro 3 enemies at once
Fully upgrade a Badge
Revisit a brain through the Collective Unconscious
Talk to Milla in her Office
Visit the Collective Unconscious
Equip 3 Pins at once
Upgrade your first Badge
Cool Hollis' Hot Streak
Shut Down the Luctopus
Make a connection in Hollis' Classroom
Achieve Rank 10
Equip your first Pin
Receive your first assignment
Combine PSI Cards with a PSI Core at the Otto-Matic
Achieve Rank 2
Navigate Loboto's Labyrinth
Consume a PSI Pop to restore some mental energy
TK throw an object to stun an enemy