Is there some built in method of exporting/importing rendered reports in the same way that we can migrate the templates? Or should I just script it instead?

I can get the list of reports with the /odata/reports endpoint in the old server, so I guess it shouldn't be too hard to script, just wanted to see if there was a built in way first.

Will I need to ensure the actual files (e.g. in the Mongo fs.files collection) have the same _id values, or are they just referenced against their filename property?

e.g. is the relationship between the reports collection and the fs.files collection between:
reports.blobName == fs.files.filename

Or does it use the ID in the filename or something, e.g. reports.blobName: reports/pdf/myTemplate/65a118152302904f0a473298.pdf => fs.files._id: 65a118152302904f0a473298?