I've talked to my avian vet about this - I have an adult GCC with one foot clubbed. When they find it young like that it's a pretty easy process to make them those little shoes. You don't necessarily need a specialist - it's just cardboard and tape! - but they'd be more likely to think about it or know about it. The bird would also likely have a better shot at actually being able to walk/move around if a specialist does it. I've had that issue before when an older GCC I had was getting her feet bandaged. Regular vet did it? Couldn't walk. Avian vet did it? Could march around just fine.
My adopted GCC had the condition for years on one of her feet and we're not sure if it was a condition she was born with or developed through injury. Since she gets around just fine, can perch (just mostly does it incorrectly), flies, doesn't have any sores, etc, we haven't done anything about it. My vet didn't seem to think it'd be helpful for her since she's older and there's been too long since she was either born with it or injured.