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