Trying to recover photos from corrupted photo library

I am trying to recover my photos from a corrupted photo library. I have repaired and restored the library. When the library opens, all the photos show as grey squares. Every time the library is closed and re-opened, it automatically triggers a restore which takes 2 hours to complete before the library opens.

I am trying to dig through the "package contents" of the photos app to hopefully recover my files from there, however, all of the folders that normally contain photos are empty. The size of the library is 378.28GB. When I dig through the package contents, I see that the file located at photoslibrary.photolibrary/resources/journal/ImportSession-change.plj is 371.52GB and seems to be one of the only files large enough to plausibly contain some media.

Does anyone know what a .plj file is or otherwise how to dig photos out of a corrupted library?

This library is very corrupted and here's its history:

• Created in iPhoto 10+ years ago
• Got corrupted by dragging/dropping it to an external hard drive then back to a Mac
• Data recovery software was run on the external hard drive and all the random files were moved into a folder
• A new Photos library was created using one of the early iterations of the Photos app
• All the recovered files were imported to this library
• This library was previously 1.8TB but over the last few weeks, I've been exporting things out in batches and deleting from the library as I go.... It's now down to 378.28GB but everything is showing up as grey squares.

I've been in contact with multiple senior advisors at Apple in the Photos department but none of them seem to have the technical expertise required to entertain this approach of going into "show package contents" and they are all just saying that if the photos app won't display the photos and a repair/restore didn't work then I'm SOL and everything is lost.