Games in `.dosz` archives not recognized

After opening an issue https://github.com/schellingb/dosbox-pure/issues/690, I believe that at least one issue does not depend on the core, I hope this is the right place to report it.

I have a DOS game, and stored the whole disk content in a dedicated directory.
I also archived the directory in a zip archive, and copied the .zip archive to a .dosz file, as described here: https://docs.libretro.com/library/dosbox_pure/#zip-files-can-be-renamed-to-dosz

This is what I've observed so far after enabling in RetroArch the dosbox-pure core.

In RetroArch I've used the "import content -> scan directory" functionality for creating a DOS playlist:

• start.exe in the folder is found and recognized
• start.exe in .zip is found and recognized
• start.exe in .dosz is not found

The expected behavior would be that games archived as .dosz are recognized, since this format is supported by the core.

Reproduce the report through RetroArch's “Import Content → Scan Directory” using the same start.exe in a folder, .zip archive, and renamed .dosz archive. Compare the scan results and trace the content-recognition path to determine why .dosz is skipped; done when the .dosz case is recognized consistently with the folder and .zip cases.