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