The Apple Developer IDE, i.e. Xcode, requires a (modern) Mac. Not having a Mac means jumping through hoops all the time (cross-platform frameworks, or cloud-based build services, or rented cloud Mac servers). Regardless if you program for Mac, iPhone, iPad, Apple Watch, Apple TV box, or Apple Vision Pro.
- You can register to become an Apple Developer using your Apple Account for free.
- You can join the Apple Developer Program for an annual fee. This step is necessary for submitting apps to the App Store. This also requires identity verification.
Get started - Apple Developer
An iOS device (iPhone) isn’t a requirement for that. But it would help a lot in your own testing, to have this hands-on verification device, if you intend to program an app for iPhone.