Unfortunately, it’s the same for Linux as for Windows. Apple does not allow you to develop native iOS apps on anything other than a Mac. And even if you can develop the app on your Linux machine, you need a Mac for debugging and to publish it to the Mac App Store.

However, you can minimize your time on macOS by using something like Flutter for example. That’s what I do at least. All development happens on Linux (elementary OS) and for the few final steps I move to macOS. I bought a cheap, low spec 13" Retina MacBook Pro which I also use for debugging Safari. Initially, I tied using macOS in a VM, but it is not worth the trouble.

It’s a setup that works very well.