"add-on for HLC" to me implies that the device has HLC installed and it adds online features to it. Please explain what you mean.
Have not seen a Android version, unless you are referring to RDP, which would be awful not to mention for those complaining about bandwidth, it would use probably around 1000 times as much data.
What I had hoped for (and asked for probably 4 or 5 years ago, I believe) is at minimum and API that other apps could access Hero Lab data from (turn on and off picks, etc.). At a minumum, that would allow others to create a variety of apps and such for viewing in whatever form they like - at a far extreme, it would enable VTT software to directly use Hero Lab's math for in-game effects, conditions, etc. Most importantly, this wold run on your own copy of hero lab classic, not depending on lone wolf's servers.