You’d have an easier time working as an IOS dev at a company where you could pivot onto their backend team.

I don't have too much experience myself, so take it with a grain of salt, but I'd imagine that your best bet would be to use your iOS experience to get a job and within that company transition into more backend work. Yes, it would require more iOS dev, but IMO that's the best way to go. You'd have to look for jobs where there would such opportunity though

The difficulty really boils down to your aptitude and the job market in your area (unless you’re lucky and can land a remote gig). I would suggest looking around for interesting jobs that are available in your area, and try to find out about their stack.

Knowing the stack will give you something solid to focus your energy on. Each language has their own idioms, and those idioms may not work well in other languages. And coming from iOS, you will soon find that out. 😅 (I say that because Im currently trying to learn macOS/Swift and it’s a whole different ball game than web development)

Find meetups in your area for the languages you’re interested in. While you should know what you’re doing in a job, it also helps to know some people too. And it never hurts to get your name out there.