Does the champion unit slot count as being in hand? Am I able to use Bone Skewer to bring it to a battlefield?

No, the Champion Unit slot does not count as being in your hand.

According to FAQ #3843, the Champion Zone functions as an extension of your hand, but it is a distinct zone. Because it is not the hand, Bone Skewer cannot be used to target a unit in the Champion Unit slot.

Bone Skewer specifically instructs you to "choose a unit from [the opponent's] hand." Since a unit in the Champion Unit slot is not in the hand, it is not a legal target for Bone Skewer.