mobile app development transactional rewards program

I am looking for a mobile app developer to create a transactional rewards program for both iOS and Android platforms. I have a list of features that I would like included in the app, and I am open to suggestions for further changes or refinements.
I don't have a lot of info to give out yet, as we are pre-start up and still confidential. App user needs to make transactions, but not always in dollar currency, may be rewards or points. Not crypto. App must be able to capture and summarize transactions for the user. Must be very secure and private. Activity must get recorded. Whole numbers only, no decimals. All platforms, all payments.
Examples of similar ideas would be airline miles programs, banks, anything that's transactional in nature, but not necessarily using dollars, also rewards programs.