Corrupted photo recovery on very old iOS device, no cloud backups

Question

I have an iPad Mini, first generation, model is A1432. It is running 9.3.5 (13G36). I decided to copy all my media from the device as none of it was backed up to iCloud/Google. I believe that some of the photos are corrupted somehow.

When I open the default photos app and look at the "Camera Roll" it shows all the photos on the device. About 30% of the photos are corrupted, somewhat randomly distributed amongst all the photos, slightly more of the older ones. The thumbnails of the corrupted photos are all grey. They appear as either portrait or landscape, suggesting the metadata is intact.

Things I have tried:

• Media sync with iTunes: this only copies the photos which aren't corrupted. iTunes doesn't seem to be able to see the corrupted images
• Create an iCloud account and sync that. Same outcome as above.
• Plug the device into a Linux machine: the contents of the DCIM directory are visible as expected. All files are shown along with expected file types (JPG/MOV) and file sizes. This seems to confirm the metadata for the corrupted files is intact. If I attempt to copy one of the corrupted images I get the following error message: There was an error copying the file into "/path/to/folder". If I click "Show more details" then I see the message Error getting file: -1: Unspecified error. Copying any of the non-corrupted images works fine.
• Syncing the content of the DCIM folder using the iFuse command line app. I don't remember exactly, it either bombed out or just copied the non-corrupted images.
• Copying the files into a zip file on the device in order to copy the files to another device. I don't remember exactly what happened here either but putting the corrupted files into an archive file failed with an error message as well.

Because the device is old I have limited options as to which apps I could install to fix the files locally. There are a number of "Photo recovery" apps on the App Store. None of them seem to do cater to my use case.

I would like to copy the corrupted files to another device so that copies exist somewhere else and I can attempt to fix them myself with various software tools. Failing that I am looking for suggestions for an app that can repair the images on the device. I'd like to avoid visiting a physical Apple store if possible.