[mcintyre1994]

To my knowledge, any recent device should have them, and location services should be available on fairly old devices - Google maintains that as part of Play Services. If you don't have an iPhone, do you have an Android device? I'd be weary to suggest developing anything until you scope out competitors - there's a LOT of apps on both platforms.

You can use play.google.com if you didn't know for Google Play apps, so if you're not an Android user that's a good place to start checking the ecosystem out. Maybe you can do something similar with the iTunes client, but I'm not too sure about that.

Oh, and another point to consider is there's far more variety among features etc on Android devices. In an attempt not to be diplomatic, that's probably a bad thing for a developer. Probably.