Yeah, there is a technical roadblock. It would only work if the browser is left visibly open. No problem on desktops but no something that could be asked of a mobile user.
I'm looking into iOS and Android app development which should open up more possibilities.
I have an array of new features that mobile users will find useful coming out in my next version. Opening up a whole new world of possibilities in the next release. I'm already using many of the hidden features myself right now and it's providing me a much deeper insight. It will take me time to build systems to display all the additional information in useful ways but once it's ready for prime time I think you'll find it useful.