Aw, I'm so sorry to read that your baby didn't make it.
Even though you had him just a short time it's obvious how much you cared + truly tried your best to help him. You may be in no rush but I think you should get another one in the near future, you'll have all the info you need now. I believe that excessive meds. given by the vet in his weakened state contributed along with the lack of uvb.
There may have been other unknown problems as well.
If you get another beardie in the future, come here with any problems before going to a vet. You'll make a good beardie parent if you get one in the future.