Good question. There needs to be an Alexa skill that can be published in one of the ISP Skill Stores. If there is an Alexa component in a mobile app that would only be published in a mobile app store, then it wouldn't be right for this competition.
Cool - sounds like it would be a fit then and an interesting use case! Make sure you read the rules around requirements since you know your project better than I do. From what I'm understanding, though, it sounds like it works.