Here is the full list of all 12 Merchant of the Skies achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Bought an island
Found the Giant Island
Put money into bank
Completed first quest
Fueled a ship
Fed the Fish God
Completed the Money Accumulation goal
Bought a new ship
Supplied inns with bread and apple juice
Built a lighthouse
Restored botanical garden