Two times Entrepreneur, Microsoft MVP for 3 years, Hands on experience of Architecting, Designing, Developing and Deploying technology solutions across various domains including Healthcare, eCommerce, Immigration, Content Security, API Architecture etc. Expert in cross platform mobile apps, iOS, Android, WP8, Web, Windows/Linux/Mac apps Need advice? Get free advice for first encounters at https://clarity.fm/pooran/FirstEncounter
https://www.filepicker.io/ is the best thing that you can integrate with this app which suits your requirement. If you are the owner of the app, you can integrate it very quickly. If not, you can suggest the app owner to do it
Feel free to call me if you need more clarification. I am consulting architect for few companies in US and India on mobile, web and windows/linux/mac apps.
You can approach Airlines for co-branding, ask shops in Airport to promote the app, ticket booking sites to promote your app in signature of the mails they send .. there are lot of avenues. What exactly are you trying to build.
Call me if needed. I am consulting architect with 14 years of experience in building iOS, Android, Windows Phone mobile apps, windows and web apps that scale.