This pup has really had it's problems
What in raw food would kill him? If he has such a compromised immune system then to me, he shouldn't be in a daycare with other pups that could pass on viruses, parasites and bacteria that would normally be pretty harmless in healthy dogs.
Also, if he truly does want to chew something due to his pica, then muzzling, if you can't crate him, is really a good idea. It is unreasonable to watch a dog 24/7, you have to sleep and work sometime
. I know somebody whose dog chewed up their sofa cushions
(brand new sofa too), so there is always something for a dog to chew on, if it wants to. I hope he does grow out of it
, that can be so dangerous and he doesn't need that on top of his other health issues