While being technically connected to the chip it is only connected to a power harvesting output that harvests energy whenever a field is present. It’s not connected to the logic side so there is no need for data transfer.
Given how small the antenna is and how power hungry the led is you can’t deviate much from the tuned frequency
To do what you’re saying you would need to make the equivalent to an xLED in multiple different tuned frequencies and the a (quite powerful) emitter that could cover the entire area where they all are and produce those frequencies.
Making the LEDs is quite simple but for the device I don’t know of any off-the-shelf options
That said you already have to usable and standard frequencies (HF, LF) and a Flipper does both. So you could use two xLEDs and a custom script on a flipper and have a two bit display.
The range would suck though and you would struggle to see and power them at the same time
[Also your username sounds french, have you seen the Biohacking Francophone group on Facebook and discord?]