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