khadinakbarlabs/expo-mobile-app-builder/add-expo-notifications-fcm

npm exec --no -- expo install expo-notifications expo-device

{
  "expo": {
    "android": { "googleServicesFile": "./google-services.json" },
    "notification": {
      "icon": "./assets/notification-icon.png",
      "color": "#ffffff",
      "androidMode": "default"
    }
  }
}

import * as Notifications from 'expo-notifications';
import * as Device from 'expo-device';
async function registerForPush() {
  if (!Device.isDevice) return;
  let { status } = await Notifications.getPermissionsAsync();
  if (status !== 'granted') {
    const r = await Notifications.requestPermissionsAsync();
    if (r.status !== 'granted') return null;
  }
  const token = (await Notifications.getDevicePushTokenAsync()).data;
  // FCM token — save to backend
  return token;
}

import * as Notifications from 'expo-notifications';
Notifications.setNotificationChannelAsync('daily-reminders', {
  name: 'Daily Reminders',
  importance: Notifications.AndroidImportance.HIGH,
  sound: 'default',
  vibrationPattern: [0, 250, 250, 250],
  lightColor: '#FF231F7C',
});

Notifications.setNotificationHandler({
  handleNotification: async () => ({
    shouldShowAlert: true,
    shouldPlaySound: false,
    shouldSetBadge: true,
  }),
});

fetch('https://exp.host/--/api/v2/push/send', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    to: deviceToken,
    title: 'Reminder',
    body: 'Time to log today',
    channelId: 'daily-reminders',
  }),
});

const notificationRoutes = new Set(['/today', '/library']);
Notifications.addNotificationResponseReceivedListener((response) => {
  const screen = response.notification.request.content.data.screen;
  if (typeof screen === 'string' && notificationRoutes.has(screen)) {
    router.push(screen);
  }
});