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