I have worked with iOS and Android for a long time, way before Swift. I love both worlds equally, and I can help you create apps that your users will love.
For iOS, I prefer Swift. It's a great language and recommended by Apple for building native iOS apps, I have done multiple apps with Swift. For Android, I have been using Kotlin lately, but I also have a lot of experience with Java. I have been learning Kotlin because it's gaining momentum, and I don't want to fall behind! I also use React Native, sometimes using React Native makes more sense over Swift because it compiles down to both iOS and Android.
I have been working with AWS Amplify lately, but I also have a lot of experience integrating various APIs, working with on-device sensors, various kit such as HomeKit, HealthKit, etc.