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?

Both. Any devices that supported ARCore and ARKit

may be do you know which version ARKit?