I specialize in React Native. After recently completing a course on React Native from Udemy (for which I am happy to provide certification if needed), I have already successfully built two react native apps for two separate organizations. One of them (look it up! - Innovations Systems Consulting) is already published on the google play store and the amazon app store while the other is in the process of verification. I feel like you could use a guy who works with react native (and firebase) and specializes in it. Looking forward to hear from you!