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