If you are looking for job for the current situation of looking for learn Trending technologies in the future. As of now you can see the Jobs with React NAtive, but deffinetly future you will get more offers with Flutter. Flutter it is now come up to support with Mobile,Web,Windows,Mac,Linux. Now you can choose which one you can learn.
As a fresher when you want to start Android developement you should have to learn first basic of android. Then you can go with Dart to learn CrosPlatform App developement with Flutter. Flutter is the future trending framwork to develope applications for web,Mobile, windows, mac... But Before start with Flutter You should have basics of Android app development with Android studio. If you want to develop ios App, should start basic developement with XCode.