@lukas.mega I ended up giving up on this approach for a few reasons:
1. the development cycle is really complicated.
2. You are pretty much limited to sharing static apis. That might be enough for most people though.
3. kotlinx library support for javascript wasn't where I needed it to be. All of a sudden I found myself trying to fill in way to many gaps by myself.
4. I tried kotlin/native and it was MUCH farther along than I expected. Kotlin/native also offers a much higher degree of sharing between platforms. I wasn't limited by sharing static apis in singleton class instances using Singleton proxy objects.
5. My iOS devs got cold feet. This is the biggest reason why. Instead my team is now developing the application using Kotlin-common modules, and we're trying out architectures with the intent of sharking code in the future with kotlin-native.
I got as far as even debugging React-native in IntelliJ. I even created a code generator to generate react-native kotlin async apis into android / swift proxy objects. This made calling back and fourth between RN much easier.