Here is the full list of all 21 PAW Patrol World achievements.
Use a pup Emote
Customise one of your postcards
Collect all postcards
Customise your pup
Collect all Pup Treat unlocks
Y'argh, wear the Pirate Costume
Play with an object
Play with 15 objects
Play with 40 objects
Jump into the past and complete a flashback mission
Jump into the past and complete all flashback missions
Complete a help request
Complete all help requests
Collect 100 pup treats
Collect 1000 pup treats
Collect all Pup Tags
Complete the Tutorial
Face Mayor Humdinger's blimp in Adventure Bay
Face Mayor Humdinger's blimp in the Jungle
Face Mayor Humdinger's blimp in the Mountain
Face Mayor Humdinger's blimp for the last time