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