I like the idea of her wearing a leash around the house, just be sure it doesn't get caught on something causing it to come down on her.
Annie B was a rescued breeder from a puppy mill and I know exactly what you are going through. EVERYTHING is so new and scary to them. Annie was
very food motivated also. I fed on a schedule as free feeding wasn't an option with her food issues. What worked good for me was to have her and Sadie (who lived for walkies) harnessed up and ready to go. I'd fix their dinners,(Who wants doggie dinner? Who's ready for dinner? Got her all excited for dinner.) I gave Annie a very small bite and then pick her up and take them outside. At first I'd just go 2 houses away, turn around so that we were facing home, put her down and with Sadie in the lead, walk back towards home. It only took a few tries and Annie figured out that the faster she got herself moving the faster she'd get to eat.
I'd lengthen the distance and that along with taking her out to do things and see things helped her to overcome her fear of going outside to walk.
Now all that said, she still preferred to be carried, because as we all know, princesses don't walk - they have slaves who carry them,
but she did learn to walk on a leash.
It took me nearly 2 years to overcome most of her fears and anxiety, please feel free to contact me if you ever have any questions. I will be more then happy to share my experiences with Annie.