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