Jerboa and wefwef are both pretty RIF-like. Jerboa can be buggy sometimes and wefwef is a web app rather than a native app, though. I’ve also been trying out Connect for Lemmy and Liftoff.
I haven’t found an app that let’s me add new communities that haven’t been added to your instance yet, though. For that, I still have to use the web browser.
Christopher Nolan has done some good big movies not based on existing book or IP: Memento, Inception, Interstellar, and Tenet.