My guess is that anyone who would have the app would have the skillset...
A friend of mine died about 15-20 years ago (damn...). He was on a bus with a bunch of researchers. One of the MDs started working on him when he collapsed. Major heart attack. Pretty much everyone else (PhD types in med fields) knew how to help. He still died. DRT. But they still tried.
The odds of surviving an out of hospital cardiac arrest is about 10% and it isn't much better in the hospital. I have been using Pulsepoint for years. It is how I found out the FD was doing a resuscitation in our hospital parking lot one time.
It was also used at a concert I was at once, by the time I was there so were a few others which is good because ideally you should be switching people doing compressions every two minutes.
I would recommend it also if you know how to do basic CPR, bodies are important to do them until an AED arrives.
bob