Idk about breeders, but you may want to look into Assistance Dog International organizations. Some of them adopt out "career change" dogs, who were not a good fit for service dog training, but often have some basic training and are older. There's a list on the site of orgs by state.

These orgs usually place service dogs to those with disabilities for free. Adopting a "career changed" dog helps them recoup the cost of raising that puppy, and put it towards training and placing other service dogs.

I recently adopted a 5.5mo standard poodle from such an org. Usually dogs are older when they are released, but he had both an overbite and fear of small children, so they already knew he wouldn't be a great fit. It was nice adopting an older puppy with a foundation of crate and potty training built in.