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