The Alexa.Discovery 3.0 capability has its origins in the Alexa Skills Kit. It is now available directly to AVS devices with an HTTP/2 connection, without requiring an AWS Lambda or maintaining a separate cloud service. The following resources provide additional context and examples: Alexa.Discovery 3; Resources and Assets
https://developer.amazon.com/en-US/docs/alexa/alexa-voice-service/alexa-discovery.html

