A word about wheelchairs.
If you are wheeling someone along at speed, do make sure they are strapped in with the safety belt. Otherwise, if the chair hits a bump in the pavement and jams, they will go sprawling and with no ability to throw arms out, it can get very nasty. I shudder to recall some of my trips with Mum along the riverwalk of the Seine, going at some speed...
Also, when getting out of cars and in a hurry, you have to make sure the feet are stuck in the footrests and the foot rests are slammed to. It's no use thinking, right, she's in a seat, let's move off and get the foot rests sorted on the pavement. Her feet will touch the ground, jam up the works and she'll go forward, maybe into the road.
Wheelchairs do need a bit of a cockpit drill or it's an accident waiting to happen.
I have bought a simple pedal exerciser of Amazon for £25, you sit in the chair and pedal, will see if that helps her. I used to walk her up the road with the wheeley Zimmer thing, I would pull and she would trot along. They didn't bother doing that at the care home so she lost the use of her legs.
Take a photo of this if you can manage it, you won't be accused charmingly by the hospital of fabricating tales of her disability when you say she's deterioated under their care.
Discourage use of slippers, they don't help with walking.
And make sure they're not on motilium, proscribed by our idiot doctor. It inhibits dopamine receptors, er, not great when Parkinson's does that all by itself. The doctor had her on it for... (brace yourselves) YEARS...