Unity - Scripting API: Application.installerName lists this simply as a read-only string. What are the possible values for this? For example, can I use it to tell the difference between someone who installed my app from the US iTunes app store vs the Canadian iTunes app store?
I think it’s not separate in different countries. Think it will always be the same. 
While not the same, this asset was very helpful: https://assetstore.unity.com/packages/tools/integration/precise-locale-65836