The GP's question was about learning IOS dev. For that, you only need the Mac. There is a simulator built in to Mac dev tools so you don't have to have an iphone. The developer account also isn't needed to learn. You only need the $99/year account to publish apps to the app store.
You can just use your Apple ID (I think that's what it's called), which is free. Some of the features are only available if you have the $99/year account.
It's possible to build iOS binaries without a mac but you have to collect a bunch of the tools yourself since Apple has made it illegal to distribute them. Of course you can't actually get the app installed on your phone without sending it to apple first (this is what eg cydia impactor does.)
IMO: that whole platform is so extremely user/developer hostile it's better to just avoid it entirely unless someone is paying you to work on it.
Definitely not suggesting that it's ideal, but if iOS dev is important to you have you considered setting up a Hackintosh or a macOS VM [1]? Typically macOS Hackintoshes/VMs have annoying issues or requirements that make it unstable for full-time desktop use, but if you're just trying to use the simulator and the Xcode build tools, maybe it's enough?
This is a pretty dramatic take. You can get a brand new mac mini with an M1 for <$1000. The price drops significantly (<$500) if you get a refurb or pick up a used one on ebay. $500 may still be a lot of money, but it's not "rich" money.