Is it permissible for a woman who has sponsored an orphan child to unveil herself in front of him after he reaches puberty, and does he become a mahram to her if she wishes to perform Hajj?

This child is a stranger to this woman. When he reaches puberty, it is not permissible for him to be alone with her, or to look at her, or to touch her, or to travel with her as a mahram (definition). Rather, he is to be treated like any other stranger. The fact that she raised him from a young age does not affect the ruling.