Can one create a full-stack mobile app solely with the use of JavaScript and React Native?

I’m a freshman majoring in software engineering. I have limited knowledge in terms of programming but I’ve learned few programming languages (Python, Java, JavaScript, a little bit of Html & css). I have great interest in app mobile development, would like to learn and get in the mobile development field as soon as possible. What is the best and fastest way to learn mobile app development? And can one create a full-stack mobile app (both iOS and Android) solely with the use of JavaScript and React Native? Thank you.