daniellerias is it possible to use custom jpg/ico for the folders?
Files Gallery already attempts to load an image from inside the folder as preview image for the folder. If you want to assign the image yourself, you can just add a file _filespreview.jpg
inside the folder.
Does this answer your question? It's not clear exactly what you mean "custom jpg/ico". You can't replace the blue folder icon, although you can change it's color for example to yellow. This is built-in SVG, styled appropriately to scale nicely within all layouts combinations. We can't just "load" and external file into there.