It is possible to open an app using Siri just by saying the name of the app. If Siri doesn't recognize the name properly (for example if it's not an english word, she won't), you can prepend it with "Open 'app'" - and Siri will match app names slightly more liberally.
Here's the question: Is it possible to include a phonetic pronunciation with your own app so that Siri will understand it without using the "open"-keyword?
Kind of like you can define pronunciation for contact-names.
This is now possible in iOS 11 using the INAlternativeAppNames key in your Info.plist as described here: https://developer.apple.com/library/content/qa/qa1950/_index.html
<key>INAlternativeAppNames</key>
<array>
<dict>
<key>INAlternativeAppName</key>
<string>Unicorn Pay</string>
<key>INAlternativeAppNamePronunciationHint</key>
<string>you nee corn pay</string>
</dict>
</array>