Here is the full list of all 11 Squishy the Suicidal Pig achievements.
Kill all bosses on insane difficulty
Kill the first 3 bosses on Hard mode!
Kill Jesse "Boom" Coyote on insane difficulty
Complete a speedrun in less than an hour
Kill The Devil on insane difficulty
Find the secret artifacts in space world
Complete all levels!
Collect all the apples in game
Kill Frosty the Snowman on insane difficulty
Survive atleast 88 seconds in the survival minigame
Kill the Big Bull-y on insane difficulty