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