Is it possible to develop a scripture app for iOS using a Windows 10 PC? According to the write-up webpage for SAB, it looks like you need a Mac computer in order to develop an app for iOS.
Unfortunately that is correct, you do need a Mac to make an iOS app. If you have a friend or colleague happy to lend you their Mac occasionally (and install SAB on it) you can do most of the work on your Windows PC and then use the Mac to test, build and update the app. SAB works the same on a MAC apart from the added features for iOS like the simulator for testing iOS apps.
I did this for a while, someone in my office had an older Mac that I could borrow. You need to move the project folder either through an external drive or memory card or through a cloud service. I saved all my projects on OneDrive on my PC and then I could access them from the Mac.
This is more time consuming and inconvenient than just buying your own Mac, the question is what do you have more of: time or money?