Possible for physical therapy to “bring back” my grandmother’s legs?

Your grandmother can bear weight enough to stand up and to reposition herself when seated. Those two abilities just by themselves are HUGE - they save her from having to sit in a wet continence pad and will help to protect her from UTIs and pressure sores.

So if she needs PT to conserve those abilities, make sure she gets it.

And if the PTs at the same time can help her even improve on what she can do at the moment, so much the better. It doesn't really matter whether "she will walk again!" or not - all mobility is good mobility and worth working towards.

What does she think? Is she willing to try?

In Hollywood movies, of course. In the real world, no. In my experience, they won't even try. They'll cite stats to you and then give up. Which I think it's pretty pathetic. They wouldn't/couldn't even get grandma to stand on her own after her fall both as an inpatient and an outpatient. They just cited stats based on her age and basically said it wasn't possible. They told me it was never their goal.

That's not to say it's not possible. After they gave up I took over. She can stand by herself with a walker again now. Working on the walking.

I think that the physical therapists will give you their best opinion and evaluation both of what is possible and about what your grandmother appears willing to attempt. They do get so tired, and it seems that they cannot at some point continue to work so hard to get so little back. Speak with her physical therapists;they are your best guide as to what is possible.
I am of course assuming she is currently getting therapy. If she is not you might ask her doctor if a PT evaluation is appropriate for her. She has a tough diagnosis. Wishing you good luck.

This sounds as though it is your wish and an understandable and caring one but if your grandmother does not have the willingness to work at PT it likely will not help. If you are relying on Medicare for this they may refuse it or not allow it to continue if she does not show progress. It's the whole leading a horse to water but not being able to force the drinking.

My mother loves PT yet she is and has been overweight for years. The AL facility is happy she takes herself down to the therapy room and gets on the reclining bike. If she gets an injury some PT is prescribed but only for a certain period of time. I have wanted her to lose weight for years but have just given up on that discussion. She just turned 89.

I have heard from others that their parent refuses to really try at PT. Your wish is a good one but may sadly not be a realistic one.