I personally owned this, until I needed a part inside of it for something else, but it worked, provided certain conditions were met: 1: range sucks! not more than 100' or so.
https://www.toprace.com/product/top...-drone-delivery-holds-up-to-7-oz-tr-66-patent
it's the cheapest option, there are a number of more on Amazon, many over $100! Seems it woudn't be terribly difficult to fabricobble some sort of release, or ever better, an electric fuse sequenced with your release to actuate a second or 2 later! Electric fuse, think model Estes rockets, they sell electric fuses ready made to ignite their rockets. at over $1/ea it is easy enough to make your own: take some very very fine wire, like what's inside of twist ties holding your bag of bread closed, cut the head off a match ant bend your wire in half, glue match head where wire is bent (the bend in the wire is now a weak point, so it will get hot and red and blow first, when running sufficient current through it. Dip wire bent, glued match head in melted wax, this will provide a bit of fuel once the wire blows igniting your match head as well as provide a modicum of waterproofing. Make a few of these, experimenting with what is the lowest voltage possible wherein your wire still confligrates. Lowest possible means a bit of a delay, keep that in mind working out your release sequence. In lieu of fireworks, have you ever overwhelmed a capacitor? reverse polarity or too much current it goes up like a ladyfinger, firecracker, m80,... depending on the size of the capacitor and load attacking it. Someone mentioned a roman candle, I like the idea of using this as a sort of machine gun, Ohh, this could be great fun, disposable aircraft fireworks battle! it could be done over a body of water! Airplanes and drones, I live in Bothell, WA a bit NE of seattle, anyone nearby want in on this? Perhaps I'll figure soomething out and create an event