suggest you confiscate your student's smartphone before sending them off on solo flight
I doubt this is a good idea, because the whole point of going solo is that you are able to prioritize and fly the airplane regardless of various temptations.
I worked with 2 instructors during my training. One didn't care about me taking quick photos on the downwind leg on my 3rd solo circuit practice. Half of those pics were useless, as I just shot them on a try-and-error approach, the other showed me focusing so strongly on flying the plane, my friends asked me: why are you so serious? I said I was waiting for the engine failure that we practiced for sooo many times...
The other instructor took photos about me before my solo flight, just to get that stuff behind us
Interestingly, in ground school, we were also educated on how to buzz something on the ground. The instructor explained that such low level flight manouvers are clearly illegal, very risky and therefore stupid, but if we ever want to try it, at least we should know how to avoid crashing. So he explained how to select the right speed not to stall out during the pull up, how to plan approach and the exit to avoid obstacles on the ground etc. Curiosity satisfied, we weren't so interested anymore in this topic afterwards, especially knowing how many extra things can kill us in low level manouvering.