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