Here is the full list of all 39 Spiritfarer achievements. It takes around 35-40 hours to unlock all of the achievements on Windows.
Accomplish your very last objective
Collect all figureheads
Complete all collections
Fully improve Elena's Cubicle
Activate all the shrines
Bring all releasable spirits to the Everdoor
Use Alex's bus stops 50 times
Have your final conversation with Hades
Light up all Lighthouses
Discover all recipes
Give a dating advice
Make all spirits reach the ecstatic mood at least once
Fully improve Buck's Lair of Wonders
Fully improve Gustav's Gallery
Build all houses and stations at least once on the boat
Shear sheeps at least 50 times
Unsubscribe from Feedorama
Fully improve Bruce and Mickey's Crib
Complete thirty errands for Francis
Fully improve Atul's Workshop
Sell at least 200 items
Fully improve Astrid's Bungalow
Have your second conversation with Hades
Tell Astrid about Giovanni's night excursions
Do not tell Astrid about Giovanni's night excursions
Find and shelter all sheeps
Fully improve Stanley's Playroom
Endure 10 of Albert's jokes
Fully improve Alice's Cottage
Fully improve Summer's Sanctuary
Make 5 spirits reach the ecstatic mood at least once
Buy at least 100 items from Raccoon Inc
Have your first conversation with Hades
Complete twelve errands for Francis
Sign up to Feedorama
Fully improve Gwen's Lodge
Complete one errand for Francis
Give Furogawa Tour's guide a tip
Make one spirit reach the ecstatic mood at least once