Sadly AVB, in the State of Victoria, the purchase and use of 'real' fireworks is essentially restricted to licensed pyrotechnicians. Civilians can only buy sparklers and 'poppers', over the counter.
The closest we could get to what you suggest, in areas where firing a shotgun is legal, is the 'Birdfrite' type of 12ga 'cracker shell' bird scaring cartridge. This is made for dispersing bird flocks at airfields - not cheap though. About AU$4 a shot!
