To create a Custom Dimension for membership status (i.e., rewards level), what scope would be applied?

The correct scope for a Custom Dimension tracking membership status is User. Membership status is an attribute that describes the user across all their sessions and hits. Once a user's membership level is known, it generally remains consistent for that user until it's explicitly changed, making it a characteristic of the user themselves, not a single interaction, session, or product. Hit scope would be incorrect because it would only apply the membership status to a single page view or event, not the user as a whole. Session scope would be too narrow as it would reset with each new session, losing the persistent nature of a membership status. Product scope is irrelevant here as membership status describes the user, not a specific product.