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