Hi Linda!
Q1: Absolutely. Before I went full time on my own stuff I worked at a really small startup building a React Native app. Being able to re-use 90% of the code between platforms was a huge competitive advantage for a startup strapped for resources. What's interesting is I believe most of the React Native development that's happening right now is by the Expo team and the stuff they're pushing out is pretty incredible and I don't see it stopping anytime soon.
Q2: I have a really close friend who worked at Apple for a bit and now works as the Director of Education for a really popular developer bootcamp. He's a Swift developer but is convinced React Native is the future. It's not really that you shouldn't learn Swift or Java (because learning is always a net positive), but if you just want to build an app, it's just unnecessary.