I just tried this last night: An inexpensive artists LED tracing panel.
I don't think the light is 100% uniform over the surface, but I also think it was "good enough" to do the job.
Note, that I was using this on a C6 HyperStar, so at its dimmest setting, it was still too bright, so I added one layer of combination CTO / ND film and then a layer of 1/8" HDPE plastic. That got me to a 0.4 second exposure with 50% histogram.
I like that it is powered by a USB cable.
I also like that it is larger than I need. I will make an enclosure for it, as I have done for my other panels, so I can use it at a dark sky site.
It's also a good back-up. My Gerd Neumann, with those dainty wires, is on its lasts legs, after many years of use and repeated repairs.
*CTO = Color Temperature Orange
*ND = Neutral Density
I don't remember but I am pretty sure it was 3420 or 3407 Roscosun Cinegel ND/CTO. (About $7 for a 20" x 24" sheet)
LED is very blue so the CTO helps if doing RGB or a one-shot-color camera. I will try to see how spread out the three peaks in the histogram are.