[Nicomedia] (a team of two) built a payload for their drone with two distinct purposes: to allow it to drop things like rose petals and to fire off fireworks. Honestly, while it is a cool idea, we are a little worried that dropping things from a height might not be a good idea (although rose petals are probably OK) and lighting off fireworks from a drone didn’t seem like a good idea at all. If you want to reproduce this, you probably need to make sure either of these things are legal in your part of the planet.
In the video below, you can see the effect. A servo tied to the drone’s controller opens the box to release the payload. In this case, the team didn’t have a spare channel so they used a separate controller, but if you had a spare channel on the flight controller, that would probably be better.
The description of the fireworks part isn’t very detailed and there’s no pictures or videos. That’s probably just as well, since that’s probably not something you ought to do, anyway. The good news is that the typical drone can’t carry anything to heavy to drop on people or blow up.