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.
Discover Fosfor’s Lair
Complete the story
Unlock all the Beelines
Defeat Screetch
Complete the temple trials
Collect the Divefish
Save Spina
Defeat the Spider
Ride the Beeline
Toot the noisemaker 100 times
Befriend a Sootling
Suck up a slug with the Slug Vacuum
Find the Post-office
Free Kickback
Blow the noisemaker
Discover the heart cluster at the bottom of the sea
Deliver the cake to the inventors house
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