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