Obirux has a brief list of what went into this modification: it required the sacrifice of two original Game Boy shells plus extra plastic, padding, and paint / dye. Then the original screen ...

Once you select Content Warning, you'll receive a new screen where you may choose ... for additional information and to 'Download' the game modification with all included dependencies.

So what’s being streamed over USB-C is a perfect real-time copy of what the player sees on the Game Boy’s native screen. In its current form, the GB Interceptor does have a couple of limitations.