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