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Re:Ask HN: Can a React Native app be integrated with CarPlay... by ecesena on Thursday January 18, 2018 @07:57PM (#16183166)
Did you look at sharing extensions by any chance? I know it's not what you're asking, but I can assume the reasons why there's nothing for CarPlay/Android Auto are very similar.

Also, you may want to check this out, it could be a starting point to get your project working: https://github.com/alinz/react-native-share-extension