@jcoelho I am very much interested in the same. I've looked at the one @droftarts mentioned and it's good for simple monitoring but I yearn for something more. There are other commercial options but many of them aren't for duet. I managed to create a simple react component that gets the status responses from the Duet but that's as far as I got! I am very new to web development so I was proud of myself for that
I think what your after can be found here:
Observing DWC with the network recorder in Chrome also helped a great deal in observing how gcode is sent, i didn't get as far as files.
I have an image in my head of a simple web layout with multiple printers in view showing perhaps only the status and percentage completion. A click on each printer expands the view a little more to show a little more info (temps, maybe fans etc.), a final click opens DWC in a new tab for that printer.
I also like the idea of a smarter print queue using the filament system to decide which printer to send a gcode file to based on it's requirements as soon as a printer is 'ready'. Also status change triggered gcode sending.
This is all very well but I'm probably several years and many headaches away from such a thing! I wish you luck and would love to look at whatever code you produce and maybe, one day, build on it. Please come back and share github links.