maggots already set in I would say it to be a down hill battle
if she seems to be suffering I would look at my options are you willing to dedicate many hours to her to treat and keep her as comfortable as you can ,
do you have a hospital coop so she don't have to deal with the others , if the wound is severe along with maggots major infection will set in . you will need to clean the wound thoroughly . can you obtain antibiotics .
is the wound life threatening/will she survive if treated
it's a hard choice best advise I can tell you is think of the birds best interest .