I want to know if it's possible to have "dynamic" app icons for both Android and iOS apps when using React Native.
Ideally, I'd like my dev / beta app to have a different icon so I can tell it apart from the production app, without having two different apps completely.
For iOS you can create multiple targets using xcode. You can do this by duplicating the configuration of your existing app, then adding the new icons to the newly created target. Here is a guide on how to do that. https://engineering.circle.com/different-app-icons-for-your-ios-beta-dev-and-release-builds-af4d209cdbfd
Android apps already have two build types, release and debug. To add new icons for the debug (dev) build simply add a new src file called debug containing the respective icons. Here is more info on how to do that. How to provide different Android app icons for different gradle buildTypes?