type DeepSignal<T extends Record<any,any>> = Signal<T> & { [K in keyof T]: DeepSignal<T[K]> };

interface Person {
  name: string;
}

const deepPersonSignal: DeepSignal<Person> = /**/;

deepPersonSignal(); // Type: Person, emits reactively the person object.
deepPersonSignal.name(); // Type: string, signal that emits reactively the name.

type DeepSignal<T extends R[]> = Signal<R[]> & { [K in keyof T]: DeepSignal<T[K]> } & {
  length: Signal<number>,
  entries: Signal<IterableIterator<[number, R]>>,
  keys: Signal<IterableIterator<number>>,
  values: Signal<IterableIterator<R>>
};

const deepPersonsSignal: DeepSignal<Person[]> = /**/;

deepPersonsSignal(); // Type: Person[], emits reactively the person array.
deepPersonsSignal[0](); // Type: Person, signal that emits reactively the first element of the array.
deepPersonsSignal[0].name(); // Type: string, signal that emits reactively the name of the first element.