State management vs functional programming in Angular applications

I am planning how to structure an Angular project. There are state management libraries in Angular to enforce immutability and control over the state, like NGRX. But if I understand correctly these kind of third party tools would be useless in a functional programming context because state would always be immutable anyway. Would it be benefical to avoid these third party tools and build services using only functional programming with only pure functions instead? Instead of importing a library for state management I could adapt a programming style that will give that same benefit. Since I don't have enough experiance with either should I learn functional programming and use a library for functional programming like fp-ts in my Angular app or should I just stick with a dedicated library for state management as most seem to do? Is it possible to fit services with only pure functions into the angular paradigm? Or will I basically just reacreate what these libraries already do if I try to do that?