expo config plugin for react-native-moengage. tested in v8.5.3

withMoEngagePlugin.js

const {
  withAppDelegate,
  withInfoPlist,
  withEntitlementsPlist,
  withAppBuildGradle,
  withMainApplication,
  withStringsXml,
  AndroidConfig,
} = require('@expo/config-plugins');
const { mergeContents } = require('@expo/config-plugins/build/utils/generateCode');

const withMoEngagePlugin = (config, { appId, sdkVersion = '12.5.04' }) => {
  // iOS
  config = withAppDelegate(config, (config) => {
    config.modResults.contents = config.modResults.contents.replace(
      /@implementation AppDelegate/,
      `#import <ReactNativeMoEngage/MoEngageInitializer.h>
#import <MoEngageSDK/MoEngageSDK.h>

@implementation AppDelegate`,
    );

    config.modResults.contents = config.modResults.contents.replace(
      /self\.initialProps = @{};/,
      `self.initialProps = @{};
      
  [[MoEngageInitializer sharedInstance] initializeDefaultInstance: launchOptions];`,
    );

    return config;
  });

  config = withInfoPlist(config, (config) => {
    config.modResults.MoEngage = {
      APP_GROUP_ID: 'GROUP_ID',
      DATA_CENTER: 'DATA_CENTER_01',
      MoEngage_APP_ID: appId,
    };

    return config;
  });

  config = withEntitlementsPlist(config, (config) => {
    const bundleIdentifier = config.ios.bundleIdentifier;
    config.modResults['com.apple.security.application-groups'] = [
      `group.${bundleIdentifier}.MoEngage`,
    ];
    return config;
  });

  // android
  config = withAppBuildGradle(config, (config) => {
    const appBuildGradle = config.modResults;
    if (appBuildGradle.language === 'groovy') {
      appBuildGradle.contents = mergeContents({
        tag: 'react-native-moengage',
        src: appBuildGradle.contents,
        anchor: /dependencies/,
        newSrc: [
          '',
          `    implementation("com.moengage:moe-android-sdk:${sdkVersion}")`,
          '    implementation("androidx.core:core:1.9.0")',
          '    implementation("androidx.appcompat:appcompat:1.4.2")',
          '    implementation("androidx.lifecycle:lifecycle-process:2.7.0")',
          '',
        ].join('\n'),
        offset: 1,
        comment: '//',
      }).contents;
    }
    return config;
  });

  config = withMainApplication(config, (config) => {
    if (config.modResults.language === 'kt') {
      const mainApplicationContents = config.modResults.contents;

      const moengageImports = `import com.moengage.core.DataCenter
import com.moengage.core.MoEngage
import com.moengage.react.MoEInitializer`;

      const moengageInitialization = `val moEngage = MoEngage.Builder(this, resources.getString(R.string.moengage_app_id))
      MoEInitializer.initializeDefaultInstance(applicationContext, moEngage)`;

      // Check if the necessary imports and initialization code are already present
      if (
        !mainApplicationContents.includes(moengageImports) ||
        !mainApplicationContents.includes(moengageInitialization)
      ) {
        // Add the necessary imports
        config.modResults.contents = mainApplicationContents.replace(
          /import com\.facebook\.react\.ReactApplication/g,
          `import com.facebook.react.ReactApplication
  ${moengageImports}`,
        );

        // Add the initialization code
        config.modResults.contents = config.modResults.contents.replace(
          /super\.onCreate\(\)/g,
          `super.onCreate()
      ${moengageInitialization}`,
        );
      }
    }
    return config;
  });

  function setStrings(strings, { name = 'expo_custom_value', value }) {
    // Helper to add string.xml JSON items or overwrite existing items with the same name.
    return AndroidConfig.Strings.setStringItem(
      [
        // XML represented as JSON
        // <string name="expo_custom_value" translatable="false">value</string>
        { $: { name, translatable: 'false' }, _: value },
      ],
      strings,
    );
  }

  config = withStringsXml(config, (config) => {
    config.modResults = setStrings(config.modResults, { name: 'moengage_app_id', value: appId });
    return config;
  });

  return config;
};

module.exports = withMoEngagePlugin;

Usage

in app.config.js import the plugin

const withMoEngagePlugin = require('./plugins/withMoEngagePlugin');

then apply it to plugins

module.exports = {
    plugins: [
        [withMoEngagePlugin, 
            { 
                appId: process.env.EXPO_PUBLIC_MOENGAGE_APP_ID, 
                sdkVersion: process.env.EXPO_PUBLIC_MOENGAGE_SDK_VERSION 
          }]
    ]
}