Follow up: there are two possible “types” of integration
Vercel Native is first managed integrations like Neon which creates a new Vercel team in your Neon account and can fully manage billing between them
Third Party is for looser integrations, like Slack which mostly just automates webhooks and api endpoints
All integrations in the marketplace are approved by Vercel so there’s no chance of accidentally getting a random dev’s custom slack plugin by mistake