Following.space *is* already integrated into many clients. Amethyst, Damus, Primal are the more popular ones, and there are others.

A good client on iOS that includes many extended Nostr features is Nostur nostur.com It also features lists that can be public, allowing other users to share, copy, and modify them. This feature is also available on Amethyst and some other clients.

A web client with many advanced features can be found at nostrudel.ninja