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
Accomplish your very last objective
Complete all collections
Activate all the shrines
Discover all recipes
Collect all figureheads
Use Alex's bus stops 50 times
Light up all Lighthouses
Bring all releasable spirits to the Everdoor
Fully improve Buck's Lair of Wonders
Fully improve Elena's Cubicle
Build all houses and stations at least once on the boat
Have your final conversation with Hades
Fully improve Gustav's Gallery
Make all spirits reach the ecstatic mood at least once
Endure 10 of Albert's jokes
Fully improve Atul's Workshop
Fully improve Stanley's Playroom
Give a dating advice
Fully improve Bruce and Mickey's Crib
Find and shelter all sheeps
Fully improve Astrid's Bungalow
Have your second conversation with Hades
Tell Astrid about Giovanni's night excursions
Unsubscribe from Feedorama
Complete thirty errands for Francis
Shear sheeps at least 50 times
Fully improve Summer's Sanctuary
Fully improve Alice's Cottage
Complete twelve errands for Francis
Buy at least 100 items from Raccoon Inc
Sell at least 200 items
Make 5 spirits reach the ecstatic mood at least once
Have your first conversation with Hades
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