Ask HN: How hard is it to change careers? Web dev – App dev

I've been interested in App development since a very young age, around 12. It spurred my interest in coding and I actually released a few (terrible, copyright-infringing) apps during middle school. I then started down the web development path by getting freelance gigs and eventually going full-time at an agency after graduating college with a CS degree. I started as an intern and worked my way up to "mid" web developer.

I love all things web development, but recently I've been wanting to dive back into iOS app development. I just don't know how hard switching career paths would be. Should I aim for junior positions and just go for it? I released a free app during my senior year of college that has like 5k downloads by now, but I don't know if that's enough to have in my portfolio.

Any advice would be appreciated!