You don't need to worry about the resolution of the device really, you need to think about how you handle the aspect ratio. For example some devices are wider than others.
I normally use a virtual resolution that is more or less the same across all devices, so using your example sizes I would make my game 1024x768 for a device that is 2048x1536 and 1024x640 on a device that is 1280x600. Then I would scale sprites based on the width (1024) to ensure that physics and movement values are consistent across devices.
I hope that helps!
Using AppGameKit V2 Tier 1