Third party API and IHostingEnvironment in Application layer?

I have 2 queries related to the open source version of aspnetboilerplate.

• If I am implementing some services that will call some other third party API APIs, where do I implement those? In application layer directly or Do the code for calling third party API in Core layer and then expose them as service using application layer?
• How do i get IHostingEnvironment .EnvironmentName in Application and core layer? Based on the Environment, i need to call the API keys stored in appsettings.json Thanks.