I "borrowed" KMSigma's PowerShell script, which exports the device templates, and converted it to export the reports.
I take absolutely 0% of the credit, as KMSigma had previously done all of the work.
I simply had to swap out the query, and that's about it.
Export Non-Default Device Templates
Using PowerShell, you should be able to export all of your reports, in separate XML files, to the directory of your choosing.
The only real issue I found is naming the exported files which contain "illegal" chars, such as the "90/95/99th Percentile..." reports.
Otherwise, I was able to run this script, then import the reports back into the system without any issues.
The exported reports appeared to function/display properly once imported back into the system, and ran.
I hope this works to get you where you need to go.
Thank you,
-Will