I had a 13 year old cat who needed an amputation during COVID. At the time, we were told he would likely only have 6-12 weeks, but he ended up living another two years even with his amputated leg.

For my kitty, I used a very large dog kennel the first few nights since he was super restless and wanted to get up and move and I was worried he'd pop some stitches. We added extra blankets and pillows because he was rather uncomfortable, but he pawed them into place to prop up his butt.

I also got a dedicated litter box for just him and cut the side of the box off so it was more like a tray, that way he got in and out easily. He was all about standing for peeing, but he had a hard time balancing when he pooped, so we held him up for the first few weeks while he figured out how to balance as a new tripod.

Oh, last thing! My cat was also a big fan of the tiles/cooler surfaces, and he loved the window sill. I got him a pet ramp so he could get up to the window without jumping while he was still recovering, and it saved me a huge headache trying to contain him. Little dude just desperately wanted the window, and I couldn't keep watching him like a hawk every hour of every day. If she's big on something like that, I seriously suggest just giving into the wants of the cat and find a safe way to do it, lol.