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