You could try keeping treats in your pocket and giving them to people to offer her when they want to pet her. Just explain that she’s shy because she’s a rescue who hasn’t been around a lot of people and I bet people would be happy to help. Have them avoid looking her in the eyes and even just gently toss the treats at first, then gradually they can try offering her one with an extended hand. She should eventually start to associate people coming up with yummy treats.
When we first started taking the puppies out and about, they were more shy than I remember our others being (probably because due to Sassy’s delayed vaccinations we didn’t start taking them out until closer to 12 weeks), and would bark at strangers. For them, just meeting lots of friendly strangers has been enough to make them more outgoing (taking them to my daughter’s softball game did wonders - nothing like having a whole team of teenaged girls come fuss over you when you are a puppy!). It was just because while they had met a variety of people at our house and were fine with it, when they encountered them out in the world it was new and strange. Hope has had a lot longer to become set in her ways, so might take more to get over it, but I would guess it’s a lot of the same problem.