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