So sorry that you lost your chameleon. You did everything you could for him. Sometimes the whole thing is just too much for them to deal with. I can only imagine how painful it might be.
Prolapses are one of the hardest things to deal with…it’s not always clear why it happened ..so figuring out if there is more going on than just the prolapse is always a concern/problem. It’s so traumatic to the chameleon IMHO, to put it back in and keep it there that some/most of them can’t cope with the trauma. In addition to that, there are issues like how to keep it in while letting the poop pass… many times the prolapses recur. There’s the issue of preventing any bacterial or fungal infections from occurring (because that moist surface is exposed to those possibilities while it’s hanging out). Should they be put on medications to prevent these possibilities…or will that cause more issues? It’s a definite crap shoot.
Your vets, IMHO seemed to know what to do and you cared enough to take good care of your chameleon.
Again…sorry for your loss. Keep him in your heart!