Here is a bit of a hit-and-miss approach, but when it hits, it’s very authentic.
I just shot a fireworks display, and the families watching it. When I turned the camera around on the families, the only light was from the fireworks themselves, and it captured the mood beautifully, as the lighting changed colors, and brightness. I used +18 gain, which ordinarily is terrible, but the graininess accentuated the effect nicely.
If I were to use any auxiliary lighting (and I wouldn’t) I’d try minimal front lighting, and something from the back and side, just to define the facial contours, and I would still let the fireworks act as the “key.”
There probably is a more “professional” approach if you are staging the whole thing. I believe the Shadowmaker device has a fireworks setting. https://www.magicgadgets.com/mg_ol_04.htm
Good luck.
— BC