Já vi um blog post de uma pessoa que fez engenharia reversa numa dessas pulseiras, pode te ajudar com algo. Não li todo o material, mas tem bastante coisa no GitHub.

• Controlling the Taylor Swift Eras Tour wristbands with Flipper Zero
• Repositório pixmob-ir-reverse-engineering
• Discussão no Hacker News

Essa pulseira mencionada no blog funciona com sinal infravermelho:

On that board are two RGB LEDs, a little microcontroller, a little bit of EEPROM and an infrared diode to receive a signal. So, simply put, PixMob works by installed a really big (and moveable) IR remote control (you can read about this on their website here) and transmitting commands to the bracelets to produce colours, fades, flashes, etc. Cute.

There are a bunch of hardware details here.

Since they are projecting infrared with moveable projector they can sweep effects around the stadium, and cover the projector with cut outs to make things like hearts. It's simple technology that works very nicely. And, of course, there's a reverse engineering community built up around this.