Is Viper architecture suitable for all types of iOS applications?

No, Viper architecture is not suitable for all types of iOS applications. While Viper provides excellent organization, modularity, and testability, it also adds complexity with the addition of several layers that comprise View, Interactor, Presenter, Entity, and Router. In case of a simple or small application, this additional complexity may be something extra because setting up and maintaining a Viper module takes more time compared to simpler architectures like MVC.
Viper is best fitted when working on large, complex applications that require maintainability, scalability, and a clear separation of concerns. MVC or MVVM will probably be more efficient for smaller or less complex applications. In straightforward applications, the rigid structure of Viper is overkill; thus, projects with complex requirements and longer-term maintenance needs are where it’s most beneficial.