컴포넌트가 화면에 잘 나타났나요? 이제 해당 버튼을 누르면 WriteScreen을 띄우도록 컴포넌트를 수정해보세요.

components/FloatingWriteButton.js

import {useNavigation} from '@react-navigation/native';
import React from 'react';
import {Platform, Pressable, StyleSheet, View} from 'react-native';
import Icon from 'react-native-vector-icons/MaterialIcons';

function FloatingWriteButton() {
  const navigation = useNavigation();
  const onPress = () => {
    navigation.navigate('Write');
  };

  return (
    <View style={styles.wrapper}>
      <Pressable
        style={({pressed}) => [
          styles.button,
          Platform.OS === 'ios' && {
            opacity: pressed ? 0.6 : 1,
          },
        ]}
        android_ripple={{color: 'white'}}
        onPress={onPress}>
        <Icon name="add" size={24} style={styles.icon} />
      </Pressable>
    </View>
  );
}

const styles = StyleSheet.create({
  (...)
});

export default FloatingWriteButton;

FloatingWriteButton을 눌렀을 때 WriteScreen이 나타나는지 확인해보세요.