When my rescue parakeet refuses to step up after months of bonding

I adopted a rescue parakeet about six months ago, and since then, I’ve been working on building trust by spending time near its cage, talking softly, and offering millet treats. The bird seems comfortable around me and even whistles back sometimes, but it absolutely refuses to step onto my finger or hand. I’ve tried different approaches like hand-feeding and gentle tapping on the perch to encourage stepping up, but no luck. I’m a bit worried because I want to handle the bird safely for cage cleaning and bonding, but I don’t want to stress it out or push too hard. Has anyone else had a rescue bird stay so independent despite lots of positive interaction? What gentle methods helped you get your parakeet comfortable with stepping up? Also, how can I tell if my bird is just cautious or genuinely fearful in this case?