Yeah, I've heard there are exercises that can make pecks that will fill up a small cup size bra convincingly, but there's no good way other than HRT and/or implants for the real deal. (It's recommended to be on HRT a while before implants because they don't look right otherwise)
Lower body is much more doable, you can get a pretty nice bum and hips doing glute bridges, lunges, kickbacks, leg lifts, etc. And there are feminizing ways to tone your waist too although I have a bit too much belly fat still to say wether it's made a difference for me... After doing these exercises for a while I've noticed A) even without dressing men treat me differently, probably subconscious, B) it's much easier to move in a feminine manner when I want to, a lot of these are activation exercises that sort of teach you to move your hips, etc. I had no idea how to get my hips to move before without basically waggling everything.
If you're trying to get convincing results anyway though you might as well get the HRT, since I imagine it's the results she doesn't like, rather than the method... Anything supplement wise has the same downsides (AND MORE!) as HRT since the only way it'll work is by telling the tissues to begin acting as female tissue, HRT is safer. That said I've heard of people transitioning with supplements and a doctor's supervision. I suggest a therapist to talk with both of you to sort this out though
