I finally got back to this…
I ended up building the following pipeline
Particle Webhook -> AWS API Gateway -> AWS Lambda
However, i want to now incorporate this into an Alexa skill and want to get the GPS location only when the particular invocation for that is made. Right now whenever the .publish() is called the AWS Lambda is called. I want to restrict that to only get the GPS value when required by the invocation is made. Any idea best way to achieve that?