Here is the full list of all 39 Spiritfarer achievements. It takes around 35-40 hours to unlock all of the achievements on Windows.
Do not tell Astrid about Giovanni's night excursions
Collect all figureheads
Complete all collections
Activate all the shrines
Give a dating advice
Discover all recipes
Use Alex's bus stops 50 times
Shear sheeps at least 50 times
Unsubscribe from Feedorama
Find and shelter all sheeps
Accomplish your very last objective
Bring all releasable spirits to the Everdoor
Light up all Lighthouses
Complete thirty errands for Francis
Endure 10 of Albert's jokes
Fully improve Gustav's Gallery
Fully improve Buck's Lair of Wonders
Fully improve Elena's Cubicle
Have your final conversation with Hades
Fully improve Astrid's Bungalow
Build all houses and stations at least once on the boat
Make all spirits reach the ecstatic mood at least once
Have your second conversation with Hades
Fully improve Bruce and Mickey's Crib
Complete twelve errands for Francis
Buy at least 100 items from Raccoon Inc
Fully improve Atul's Workshop
Tell Astrid about Giovanni's night excursions
Fully improve Stanley's Playroom
Fully improve Summer's Sanctuary
Fully improve Alice's Cottage
Sell at least 200 items
Sign up to Feedorama
Make 5 spirits reach the ecstatic mood at least once
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