Here is the full list of all 22 Smushi Come Home achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Craft every skin
Talk to the onion
Discover every mushroom
Unite both capybara siblings
Collect 400 crystals
Cleanse the corruption
Acquire all wind essences
Acquire all spores of energy
Rescue Chungy
Beat the diver challenge
Beat the nectar gathering high score
Explode the river drain
Help a friend gather two acorns
Rescue both lost lovers
Beat all three glider game challenges
Beat both obstacle courses
Collect 200 crystals
Feed the lizard two berries
Knock down all the strawberries
Restore all flower shrines
Collect 100 crystals
Bring both relics to the researcher