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
Unite both capybara siblings
Cleanse the corruption
Collect 400 crystals
Discover every mushroom
Acquire all wind essences
Acquire all spores of energy
Rescue Chungy
Beat the diver challenge
Explode the river drain
Rescue both lost lovers
Beat both obstacle courses
Beat all three glider game challenges
Beat the nectar gathering high score
Help a friend gather two acorns
Collect 200 crystals
Feed the lizard two berries
Restore all flower shrines
Knock down all the strawberries
Collect 100 crystals
Bring both relics to the researcher