so should you use react-native or xamarin now? how much 'write-once-run-everywhere' is available in xamarin vs react-native? I've long avoided .net and c# but

so should you use react-native or xamarin now? how much 'write-once-run-everywhere' is available in xamarin vs react-native? I've long avoided .net and c# but now I'm getting interested because these things are becoming open source.