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