You could start with an allowlist approach; add servers to federation when you see they have content/people you want to connect with. Over time the list will gr

You could start with an allowlist approach; add servers to federation when you see they have content/people you want to connect with. Over time the list will grow. E.g. start with the biggest ones and maybe some that are specific to your interests. Over time you will see people resharing posts and commenting on threads from other instances and you can add those as well. If you run a server for other users you could have an account set up for your users to ping with servers they want you to add.