Ideas for Advocacy Activities with Fortune 100 Customer

I feel like I saw something somewhere recently about advocacy activities that were focused on building stickiness and advocacy within existing accounts, but I have no idea where. We've got a Fortune 100 customer with an internal champion who is super enthusiastic about our product. He's a design partner for our new product offerings, and he's interested in doing some kind of advocacy stuff with us, but there's some hesitancy (rightly so, probably) about going through internal approvals. What he really wants is to get more teams using our product and to share the things his team has done more widely. I am meeting with him on Monday, and I want to come with some ideas on how we can help build materials for him to share and use with other teams, like a short video, an internal-only case study, or templates for his how-to docs. Is there something I'm missing that would also be useful?