When you download the phonegap.zip file from the cloud portal using 'build yourself', you can build it using XCode on a Mac. I have done that to simulate an iPad Pro for getting screenshots.
Check the hybrid app template, on which the phonegap builds are based, for details on configuring your Mac. After going trough that, you will have a working XCode project, which you can run in the simulator.
For Android you can also run emulators on your local machine to debug, for this you should check out the 'do it yourself' option when building your Mobile App in the Developer portal along with this blog.
Not sure if this would help, but I would check out lonely screen. I know some of my coworkers have used this in the past when developing a mobile application.
Here is the link to their website:
I have never developed a cross-platform app because I am a native app developer. If you have some queries regarding mobile app development tools and testing tools you can refer to this article: https://www.infoq.com/news/2014/04/phonegap-developer-app/.
According to this article, “..enables even testing iOS apps from a Windows machine, according to Raymond Camden, an Adobe PhoneGap developer.”