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