I am making assumptions about Wiley and the severity of his separation issues, so take what I say with a grain of salt.
Separation anxiety IS treatable but it is a long road, and medication like fluoxetine is often a large player on that road. I know you are looking for resources to surrender the dog. But if your daughter is looking for training resources, I recommend Malena DeMartini's "Mission Possible" course. She is the nation's leading expert for separation anxiety and her course is virtual, self-led, but with professional advice. I believe it is $99.
Not many shelters will take a dog with true separation anxiety. And if I were you I would be wary, and ask plenty of questions, if a shelter easily said yes. I don't fault owners for thinking that surrendering is a kind option as it gives the dog another chance at a home. But the reality is dogs with severe separation anxiety are very hard to place. My heart goes out to your daughter because people really do start to feel like prisoners in their own homes when they have SA dogs. That said, when people are walking through a shelter looking for a nice companion, how many are going to willingly take in a dog who literally cannot be left alone without significant investment in daycare, sitters, medication, etc? So the truth of the matter is dogs with severe behavior challenges like this sit in shelters longer. And a shelter is one of the worst places for dogs with SA. Not only are the dogs rarely ever with people, but they live in pretty much a box surrounded by other distressed, barking dogs day in and day out. On top of that, SA dogs present poorly because when they do meet people, they are often frantic and their existing anxiety compounded by shelter stress may also cause them to present other undesirable behaviors. These dogs are also poor candidates for fostering because even foster families have normal needs, like getting out of the house to get groceries. For those reasons, I think it is inhumane to surrender a dog with severe SA to a shelter, even if the choice is considered with the best of intentions for all parties. I think a home to home situation is much better, but it is still a hard sell.
Again, I am making the assumption that Wiley has classic "separation anxiety" and I could be wrong. Though even by your post, it sounds bad but not horrible. Destruction is normal. I've seen dogs literally try to claw their way out to the point where their nails are bloody stumps, and they sit, shaking, in their own blood and urine every time they are alone. Also dogs who jump out of glass windows in order to find their person. So, it could be worse. But it could be better. If your daughter does seek to rehome, I think it would be reasonable to ask that the adopters put the 'rehoming fee' towards signing up for the training program, so that they show initiative in helping Wiley get better. But she would need to be absolutely transparent about the degree of his anxiety. I've spent hours of my life counseling would-be adopters about separation anxiety because when people see a cute dog, they literally cannot envision what it is like to live with an SA dog. I ask questions like "who will watch this dog be when you need to do a 20 min grocery trip?" And when they give a casual answer (ex. 'oh he'll be fine for 20min') I paint them the very real picture of how much damage a dog can do in 20 min.
Best of luck.
EDIT: Meant to add one more thing. I am in no way speaking for 'shelters' as a whole because each is different. But even if a shelter was willing to take Wiley, there is still the possibility that they may euthanize him if his behavior deteriorates in the shelter. They would make a difficult choice like that for the sake of the animals' quality of life. Different shelters have different policies on if owners are notified should that decision become a possibility.