In the Apple App Store and the Google Play store you can define in which countries and regions your app is available.
Google play store
You can log in to Google Play Console | Google Play Console and check this under the Countries/regions section (Distribute app releases to specific countries - Play Console Help )
Apple App Store
For iOS you can check the availability for live apps by following the steps from this article: https://help.apple.com/app-store-connect/#/devcdda55918