Here is the full list of all 31 Yoku's Island Express achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
Find the Post-office
Free Kickback
Blow the noisemaker
Suck up a slug with the Slug Vacuum
Save Spina
Collect the Divefish
Complete the temple trials
Defeat Screetch
Befriend a Sootling
Defeat the Spider
Complete the story
Discover the heart cluster at the bottom of the sea
Discover Fosfor’s Lair
Ride the Beeline
Unlock all the Beelines
Deliver the cake to the inventors house
Toot the noisemaker 100 times
Toot the noisemaker 1000 times
Customise Yoku’s ball
Become the Postmaster
Activate all Scarabs
Take the surviving egg to Dipperloaf
Collect all Wickerlings
Hatch the God Egg
Complete Willo's quest
Complete Rinri's quest
Complete Thorn quest
Unlock all treasure chests
Get the biggest wallet
Try every ball style
Collect every ability upgrade