Android and IOS app development for medical device using BLE

I am looking for an experienced Android and iOS app developer to build an app for a medical device. This app must perform data logging and analysis as well as real-time monitoring, and must be able to integrate with the medical device. It is important for me that it not just be compatible but look great across all viewing platforms. I have a detailed design of what I am looking for, which I am excited to share. I am also looking for this app to be compatible with more than two past versions of both Android and iOS. I am counting on your expertise in making this a reality. Ultimately, I am hoping for a stunning app that functions perfectly and provides a valuable user experience.