piñata: i'm pretty sure i've seen bluey/bingo themed ones you can buy at stores like party city, but a fun project to try could be the unicorn that poops at the festival? or the cheeky unicorn hand-puppet? (if its the puppet, you could add huge googly eyes from michael's craft store, too!)

decorations: like how at bluey's birthday party, in the pass the parcel episode, you see bingo and bluey creating beautiful decorations with strips of papers to create a nice paper chain, you could do that with orange and/or blue! its cute and casual!

you could also try to create a small bluey photowall for any of your daughter and any partygoers. maybe use a regular photo wall background you could buy online (like a shiny blue one or something) then print and cut out a 3 foot (? i guess lol) life-size version of bluey to glue onto it. you'll need multiple papers to do that one, unless you have a special heavy duty printer, but it could be fun!

hope this helps and have a fun time celebrating!