I'll have a job interview in a fintech company that makes an app I use a lot. I've reverse engineered it and written a new version from scratch that consumes their API to add the features I think it lacks.
I assume they'll ask what I've been doing recently or what's my relationship with their product. I feel that already knowing their API and having architected, written code and tests for their product is a plus but I'm a bit afraid they take it the wrong way (their app is obfuscated and the app handles money).
Should I mention that in the interview? If so, how do I approach that?