Hi,
A scam,
So did he use the device or infected a website ? And infecting website with what , an ActiveX from 90s ?
And if you are using a laptop, the led flash is embeded with the webcam so it's impossible to activate the camera without the flashlight (the small LED) (correct me if I'm wrong).
And then the pixel. Is it possible ? Yes, did your mail reader signal it ? No, so there is none. The pixel may be small but not for the mail reader who will block it automaticlly (Thunderbird per example).
I don't think there's a threat here.