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