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