There's no requirement that you must use a "Pro" model in order to use the debugging tools in Safari. The MacBook Air has the exact same functionality. In fact there's no specific hardware requirement for this - it might as well be macOS running in a virtual machine on a computer running Windows.
Ofcourse there are other differences between the Pro and Air machines regarding performance, screen size, weight, etc.
Depending on your needs, you might be able to get by with renting a remote Mac online. Several services exists (Such as MacStadium) that allows you to rent Mac for a month or even by the hour. The Mac is accessed with remote desktop software. You could use remote USB software such as VirtualHere to access your iPad over USB from the remote Mac.
In order to do remote debugging of the web site on the iPad, you'll need to first enable it on the iPad:
Then plugin the iPad with a USB cable to the computer, and then do the following in Safari:
Now you have the web inspector (what you call debugger) setup.
After opening your web site on the iPad, then open Safari on the computer and access the Develop menu. You'll find your iPad in the list, where you can choose your web site - the web inspector with debugger will be shown on the computer.