This is a feature I would also appreciate.
mcpuk file browser allows creating a
nested folder structure, and to display preview of images.
I don't know if it was able to create thumbnails in several resolutions. It is quite old codebase. It is for sure working fine, at least with PHP 7.1 and maybe with PHP 7.2 and later.
For a working implementation, it was in use in MODx Evolution 1.1.
Here's the download URL of MODx Evo 1.1 on GitHub :
https://github.com/modxcms/evolution/archive/refs/tags/1.1.zipMcpuk itself is located in "/manager/media/browser".
It seems that Mcpuk can also be downloded from Sourceforge.
However, the folder stucture of the latest release seems quite different from the one that I can see in MODx Evo.
After this release, the codebase evolved considerably for both MODx Evo (now Evo CMS) and MODx Revolution, so that don't know which file browser they are using nowaday.
The are things that I like in the media browser that AbanteCart is currently using, but for large shops, the ability to organize pictures in a nested folder struture would be highly appreciated.