Ducks can rebound from awful injuries, that I know.
I don't know if it would be a good idea, exactly, but I wonder if the foot could be amputated. Did the vet say anything about that? There are now duck foot prosthetics available.
One risk is infection - did the vet provide any antibiotic?
Perhaps you can make a cast or a splint to hold the foot together properly for it to heal.
Giving her time floating in lukewarm water may help - also, you might try setting up a hammock or sling to keep the weight off her foot.
Good nutrition, including poultry vitamins in her water once a week, is always a good idea.
And comfrey is an herb you can put on the foot - it is said to help accelerate healing (there was a study done and it does stimulate healthy cell reproduction).
The vet put a sort of splint on for 4 days..... Being it is broke where it is there is no way to splint it really & he said if we keep it bandaged up he is afraid of the foot & webbing would rot.
There are no open wounds really anymore. Vet didn't see any sign of infection so he didn't give her any antibiotics.
Even though I live in a very country area & my vet is country as well he still doesn't really deal with ducks or any birds really.
More horses, cows, cats & dogs. I have called vets all over my state & had no luck with any being experienced with ducks. Even the wildlife places around here.
So I'm kinda winging it here.