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