Is there any way to build IOS app on Windows?

NativeScript CLI & Sidekick support cloud build that would help you build your app from a Windows machine, basically the source code is uploaded to a remote machine and built there, then you could directly run the package on your local iOS device.

But unfortunately it is not possible to run the iOS Simulator on Windows at all, which is a limitation from Apple.

It is possible. You can run macOS Virtual Machine, check this article

It will give you fully functional OS, so you can do updates, register developer account, install Xcode and so on.

It is even possible to publish to App Store without even have Mac and iOS device. It works quite good if you have a strong machine, even when you run iOS Simulator.

But:

It is against the Apple EULA to run any macOS on non-Apple hardware, directly on the hardware or in a virtual machine.

SideKick will help you on Windows (with Cloud Build option), but you need to have an iOS device to test your app.