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