Federation is user-driven, not admin-driven: if you subscribe to content on a new instance, that instance will become federated with yours by default.
Defederation is admin-driven, but if done right it’s an added value: if you agree with the admins’ policies, they’re filtering out content you wouldn’t want to see anyway. So it should suffice to make one account on an instance whose policies you agree with—or barring that, an instance that never defederates from anyone.
And for maximum control, you can always start your own instance that just hosts your own account.