Is Handheld AR (UE 4.19) use ARCore or ARKit?

In Unreal Engine 4.19 Release note, they are mentioning about Handheld AR.
Is it using ARCore or ARKit? Or an Augmented Reality Version of Unreal Engine.
How many android or ios devices support it?

Unreal implements both APIs, and will target your device automatically when you deploy it. It now uses unified functions calls for both targets. Check ARCore and ARKit’s home pages for a list of supported devices; Unreal simply implements those API, which technically should be compatible with whatever each API supports.

I just used the template for our tests on both families of phones(iPhone 8s and Google Pixel) and it works well.