Unreal Engine 4.17 Preview

Hello,
I would like to understand what’s going on about augmented reality in Unreal, because I’m bit confused and I can’t wait to develop AR app with Unreal.
We have the project Tango in 4.17, but it works only with some devices: is that correct?
Then we will have ARKit im 4.17, but it’s only for iOS: is that correct?
If they are both correct, what about all the other devices?
Thank you very much.