You can use the Krita plugin Buli-Commander to select the images in a file manager you start from within Krita. It can show all KRA’s and many more picture-file-formats as thumbnails, and so much more.
Or you could detour to XnView MP, a multiplatform image viewer (free) that can also browse and display KRA’s you can then drag and drop them into Krita, or XYplorer, a very versatile replacement for Windows Explorer (it probably will make you forget Windows-Explorer) that can also display KRA thumbnails. Unlike XnView MP, XYplorer has the advantage of being a full-featured file manager from which you double-click to open the images in Krita, but the disadvantage that it comes at a cost, about $70 for a lifetime license, there is also a cheaper license.
Michelist