Compila sin errores. La navegación va de register a home, y redux está implementado. El registro aparece en la DB.

App.js

 import { createStore, applyMiddleware } from 'redux';
 import rootReducer from './redux/reducers'
 import thunk from 'redux-thunk'
-import { connect } from 'react-redux'
+/*import { connect } from 'react-redux'
 import { bindActionCreators } from 'redux' 
-import { fetchUser } from './redux/actions/index'
+import { fetchUser } from './redux/actions/index'*/
 /*const seConfig = {
   apiKey: "AIzaSyDW-ABAQ3r_WR7C7WC_3VprL77NcAoitJI",
   authDomain: "freehand-d8ecd.firebaseapp.com",
   }
 }
 
-const mapStateToProps = (store) => ({
+export default App
+/*const mapStateToProps = (store) => ({
   currentUser: store.userState.currentUser
 })
 const mapDispatchProps = (dispatch) => bindActionCreators({fetchUser}, dispatch);
 
-export default connect(mapStateToProps, mapDispatchProps)(App);
+export default connect(mapStateToProps, mapDispatchProps)(App);*/

screens/main/Home_page.js

 import { styles } from "../../config/styles";
 import { TextInput, TouchableWithoutFeedback, Keyboard, ImageBackground} from "react-native";
 
-export default function Home_page({navigation}) {
+
+import { connect } from 'react-redux'
+import { bindActionCreators } from 'redux' 
+import { fetchUser } from '../../redux/actions/index'
+
+export function Home_page({navigation}) {
   const [threads, setThreads] = useState([]);  
   const [loading, setLoading] = useState(true);
 
     );
   }
 
+const mapStateToProps = (store) => ({
+  currentUser: store.userState.currentUser
+})
+const mapDispatchProps = (dispatch) => bindActionCreators({fetchUser}, dispatch);
 
+export default connect(mapStateToProps, mapDispatchProps)(Home_page);