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