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