I did the opposite. Started as native iOS dev for 3 years, then picked up React as a hobby, then started a new job with React-Native, and now I do full-stack. I

I did the opposite. Started as native iOS dev for 3 years, then picked up React as a hobby, then started a new job with React-Native, and now I do full-stack. I've also done a lot of back-end both as a hobby and at work. As others said, play with different tools and do what you enjoy!