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