I tried to add ExifTool to DOpus-Scripting-Extensions project. Unfortunately, their C++ library doesn't support Windows 
Thus, it will be hard for DOpus developers to integrate it, even if they wanted to.
Using an external GUI is probably the best option. You can also use the ExifTool directly by creating a context menu element and execute the ExifTool.exe image.png command. It will show the console window with all information about the image. It is a poor man's GUI 