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