How big of an issue is it to target iOS as a platform on a PC these days with the rise of Flutter, etc? I'm looking to get into app development, but don't have a Mac, nor would I like to buy one if I can avoid it.
Flutter is nice. Yes, a single codebase typically works both on Android & iOS (sometimes, a little tweaking on each platform is needed).
The problem is: you can't avoid iOS SDK for iOS development. This is not Flutter-specific, BTW, but everything: React Native, Ionic, Xamarin, Pascal etc etc. So you need to have either a Mac machine, or access to Mac cloud server.
I vote the former, because it makes debugging easier.
[0] https://blog.codemagic.io/how-to-develop-and-distribute-ios-...
Whatever solution you pick for iOS dev: Flutter, React Native, Xamarin etc etc, in the end we will always meet the same thing: iOS SDK. And iOS SDK only runs on Mac, unlike Android.
Unless Apple decide to port their SDK to Windows/Linux (which I believe will not happen), you can't practically avoid Mac.
You can count on the framework to abstract away big significant parts of your app (business logic, UI) but some of the nuances you will probably have to tweak yourself. Launcher icons, handling notches, device specific features, and other weird oddities.
At least in the React Native community, you can often get away with building to the device only once every native dependency change. This becomes a better experience with Expo though