Hey all, I've created a catio (cat patio) for my two cats in a window well next to my desk. They absolutely love it, but I would like to make it even better for them by using real grass. Currently, I have a pretty good artificial grass in there that they love to lay in and stays green year 'round, which is fine enough. But I would really love to give them some real grass (or moss) to lay on and maybe even munch on.

So, with that backstory, I would love to find a grass that has the following traits.

1. Comfortable and safe for cats (both internally and externally)
2. Stays relatively short since I can't exactly get a lawn mower
3. Doesn't require a lot of sun

It would also be a bonus if it were okay with more arid climates, because I would prefer to minimize watering as much as possible.

My mind goes to something like Spanish Moss since it stays relatively short and is pretty comfy, but I'm not sure if that's the best option, so I wanted to ask people more experience than me.

Picture of the window well in its current state and one of its occupants for reference below.

And for anyone concerned, the well is closed in with a grate and some chicken wire so they can't slip out. They are not outdoor cats, but we do take them out on harnesses for walks. They are treated for pests like tics and mites as a precaution.

Thanks anyone who answers!