Using Redux-Persist with REST API

I have followed countless tutorials on redux-persist and believe I am implementing it correct in my redux-toolkit app. However, I think there's a disconnect in fundamental understanding on my end. Can I use persist on an application that uses REST API or do I need to setup my on backend server for it to work? And if you cant use persist for an app that uses REST API, how would I go about getting state to persist on an app that uses Redux-Toolkit? In Application in my browser's devtools, it shows that my state has been saved but when I close the browser window and open it back up, I find that my shopping cart is empty. Here's my code just in case I'm missing something:

Store js

import cartReducer from "./features/Cart/cartSlice"
import modalReducer from "./features/Modal/modalSlice"

//Persist
import { persistStore, persistReducer } from "redux-persist";
import storage from "redux-persist/lib/storage";



const persistConfig = {
    key: "persist-key",
    storage
}

const persistedReducer = persistReducer(persistConfig, cartReducer)

const store = configureStore({
    reducer: {
        persistedReducer: persistedReducer,
        cart: cartReducer,
        modal: modalReducer,
    },
    middleware: (getDefaultMiddleware) => getDefaultMiddleware({
        serializableCheck: false
    })
})

const persistor = persistStore(store)

export default store;
export { persistor }

Index js

import ReactDOM from 'react-dom/client';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';


import store, {persistor} from "./store"
import { PersistGate } from 'redux-persist/integration/react';
import { Provider } from 'react-redux';

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(
  <React.StrictMode>
    <Provider store={store}>
      <PersistGate persistor={persistor}>
      <App />
      </PersistGate>
    </Provider>
  </React.StrictMode>
);

Any help will be appreciated.