react-native-maps provides a Map component that uses Apple Maps or Google Maps on iOS and Google Maps on Android. Expo uses react-native-maps at react-community/react-native-maps. No setup required for use within the Expo client app. See below for instructions on how to configure for deployment as a standalone app on Android and iOS.
Since your app is most likely using App Signing by Google Play, you will need to grab their app signing certificate in production rather than the upload certificate returned by expo fetch:android:hashes. You can do this by grabbing the signature from Play Console -> Your App -> Release management -> App signing, and then going to the API Dashboard -> Credentials and adding the signature to your existing credential.
Note: The API key can be accessed through your app's Constants (via Constants.manifest.android.config.googleMaps.apiKey) if you'd prefer not to have it in your code directly.
If you want to add MapView with Google Maps to an ExpoKit (ejected) project on iOS, you may need to manually provide a key by calling:
[GMSServices provideApiKey:@"your api key"]
Alternatively, you can provide the GMSApiKey key in your app's Info.plist and ExpoKit will pick it up automatically. If you ejected after already configuring Google Maps, the eject step may have already provided this for you.
Web is experimental! You may need to add the web target to your Expo app.
To use this in web, add the following script to your web/index.html. This script may already be present, if this is the case, just replace the API_KEY with your Google Maps API key which you can obtain here: Google Maps: Get API key