This is probably the simplest conversion script, it takes all .png files in the current directory (.png files, texconv.exe and the .bat file must be in the same directory) and converts them to a R8G8B8A8 .dds file. It should execute by a simple double-click (windows might complain however, so make sure to check for viruses! ).
ConvertDDS.bat (85 Bytes)
I noticed however that texconv.exe doesn’t support uncompressed R8G8B8 specifically (for various reasons it makes sence), generally converting to DXT1 (BC1_UNORM for texconv) is prefered in that case (but it is also a compression, so it depends on what you are actually using the .dds textures for). But if you want explicitly R8B8G8 without compression i was able to do it with imagemagick.
Finally, the script is very simple and you might be interested in recursive behavior etc. but it should be easy to extend by reading the available commands in the related github link i posted. The .bat file is a simple .txt file and can be edited if opened in text editor (using the console instead works to ;).