I really do understand not wanting to give up on such a young bird. Goddess knows I've tried weeks and months of every treatment I could think of to save my own.
Crop issues are not always treatable. This one sounds like an especially tough one. I wouldn't give up, though.
There is one thing you can try that might help. It sort of duplicates what a crop bra would do. I hold the chicken in my lap and massage the crop. I do it several times a day. I've never had a chicken object to this.
I begin by gently lifting the crop and supporting it. This alone often helps the crop to partially empty. Then I kneed the crop with my finger tips, focusing on any hard spots, trying to break them up. If the crop is mostly liquid, it's necessary to be especially careful and gentle so as not to force the liquid into the esophagus.
This can keep the contents from stagnating, and it gets food out of the crop and into the proventriculus so nutrients can start to be absorbed in the intestines and keep her alive.
It may be that this is a genetic defect and it will not improve, but there's also a small chance the chest muscles on the young pullet can strengthen and eventually hold the crop in the proper position. Sometimes long shots pay off. It's always worth a try.
It would be worth it to try the crop bra along with the massage. If the crop is supported, it may give the chest muscles a little help, and they may be more apt to strengthen.