From what I understand about the fediverse, everything that Meta already knows about you and your content is going to remain the same. Federated or not, they will only have access to info you make public, and how much that is is entirely up to your instance. Even if Meta never wanted to join and federate with others, they could still scrape the same info and use as they see fit for training AI, duplicating posts or whatever.
So basically you don't have to do anything, Meta cannot demand any extra data from you that your instance owner does not want to share. If you are worried your instance owner might do some deal with Meta for your data, then you can better control that with self hosting.