Here is the full list of all 14 Pizza Possum achievements.
Have 4 guards chasing you at the same time
Gobble up the caprese salad
Unlock your first item
Collect 30,000 points worth of food
Chase an NPC halfway across the island
Eat Bella Chonki's gigantic pizza
Stun three guards at once
Unlock every item in the game
Visit every region on the island
Unlock the smoke bomb
Find all Zeppole on the island
Collect a crown from Bella
Earn two crowns
Rob Bella of her delicious pizza three times