LLMs are useful for a variety of things. What you're describing would only be useful for students cheating on assignments. I doubt that it will attract the many millions of dollars spent on training GPT-4.
But more importantly, LLMs are always available over the Internet. If students need to use a physical device to cheat, that's already a big step forward, since it increases the chance of detection — a key factor in deterring misbehavior.
