An appointment with the COAS takes a lot of time, generally months beforehand .. even weeks for people close to him.
However, I may forward the suggestion if you wish through mutual links.
The COAS is an avid technology fan and is a major force in the army's tech upgrade...perhaps the idea of an online Q&A may appeal to him.
However, be very sure that the current COAS has made it his priority to NOT involve the army in any political image and generally avoids the personal limelight as much as his chair can.
If anything, ISPR may arrange it or otherwise..
but chances are it may be refused in the light of the country's situation.