I'm trying to understand something.The sleep app is developed...

I'm trying to understand something.
The sleep app is developed for iOS but the handheld is developed for Andriod devices.

This leads to many questions.

1: Why Andriod and not both, Andriod and iOS?
2: For a start up company, why develop on 2 different platforms, Sleep check on iOS and ResApp-DX on Andriod. This also raises more questions. If developing in Java language then the apps should easily be cross-platform meaning this device should work on both, and both apps should be launching on both OS.
3: Do we know if ResApp-DX is/was developed for both iOS and Andriod?

If anyone has this info and can shed some light on this for me, that would be great!

Cheers,
Dave