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