Your idea of the proximity-sensor is fully understandable, but as it is, this is not possible. So if you need such a feature, you either have to reprogramme it yourself or file a bug to Blackvue / Pittasoft, and cross your toes that in some future FW-release this will happen.
The "Wifi On" or "Wifi Off"-speak is NOT currently possible to turn off. I wondered the same, but going thru the voice-feedback settings, no such thing is to be found. I've completely muted all the feedbacks, except event-beeps.
It has brought a lot more silence to my car, instead of hearing recording mode changes, powering down, Blackvue for your safe driving, Starting normal recording etc etc.
Perhaps one day, the Wifi On / Off will be able to be muted as well.