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