I have seen videos of little Charlie. I have never seen a more serene expression on a sleeping child’s face. Charlie has several issues which you enumerated; but pain clearly isn’t one of them.
Are you sure he is not constantly under sedation?
Again, whatever procedure is the best for Charlie and won’t cause him additional suffering is what I wish for the little guy. No one should be subjected to experimental medical procedures if there is no hope, no precedence history, and medical opinions are sharply divided.
Your post jogged my memory from 15 years back. We had this beautiful Lhasa Apso female dog who was 14 years old at the time. Her name was Jillian. She was just a marvelous pet. She was our first baby, and then followed by our own 2 wonderful daughters. Jillian was very smart, I swear she understood at least 2 dozen English words. She was lovable, very protective with a loud bark for a 15 lb dog, pretty, and never was sick in 14 years. Then it happened. She got sick. Stopped eating. Lost weight. The vet diagnosed cancer of internal organs. All 4 of us were heartbroken over the news. The vet said it was terminal and she was in lot of pain. Duh...we already knew that because the always cheerful dog was laying in fetal position whimpering. So we take Jillian to the Vet's office to put her to sleep. There we were escorted to a private room. The vet gave Jillian a shot of some sedative. It must be strong because she immediately stopped whimpering and began snoring which she always did when well. The vet told us to take as long as we wish to say goodbye. My wife and I held Jillian in our arms, caressed her, and we were both bawling. But Jillian looked peaceful, no sign of pain on her face. After a long time we called the vet, he administered a second shot, and that made her heart stop.