Is there any way to develop iOS apps on a MacPro 2,1 in 2019?

I wanted to run cordova on some my apps so that I can test them for iOS. Running cordova run ios on a windows system will complain:

xcodebuild was not found. Please install version 9.0.0 or greater from App Store

I had already read that you needed a Mac in order to build iOS apps so not knowing much about Apple computers I bought an old Mac Pro for $100 thinking it would work.

I later learned this Mac Pro is running Mac OS 10.6.8 and that it cannot be upgraded further. There's a Mojave patch that works on MacPro 3,1 and later won't work on MacPro 2,1 The xcode in the App Store requires Mojave, which I think is 10.14.xx

Is there any work around to build these apps on this old MacPro 2,1 running 10.6.8?

Is there any way to develop iOS apps on a MacPro 2,1 in 2019?

No. I'm afraid you've bought yourself a boat anchor. Developing iOS applications requires you to run a current version of XCode, which in turn requires a current version of macOS.

The MacPro2,1 was produced between mid-2007 and early 2008; the processor in this machine does not support some instructions which are used in current versions of macOS. There is no known way of working around this, and hobbyist projects to enable the use of macOS on unsupported hardware have abandoned all attempts to provide support.

The Mac in question does not support a new enough macOS to install the latest versions of Xcode required to build an app that can on the App Store.

However, you could use an online build service in order to be able to develop and test apps on this Mac. For example you could use your Cordova project with Monaca - they have a free plan where you can do 2 builds a day for free. Similarly you can use your Cordova project with the Adobe PhoneGap service - although not for free.