Is she spayed? If not, she’ll be less territorial if you get her spayed and it has the added bonus of eliminating the risk of uterine cancer. I have cats and rabbits and my first rabbit forced my old fat cat to cuddle with him all the time. Then I got him a bunny companion and he forgot the cat even exists. He 10,000% prefers the company of other rabbits. Based on my own experiences I would say she’ll be much happier if you can get her a rabbit.
They said if you just can’t get her a rabbit, you don’t want a kitten. You are thinking of getting her a companion because you won’t be home as much as and kittens are insane, energetic and learning to hunt. If you go with a cat, for the rabbit’s safety it would be best to get one that’s at least 2 years old and preferably ask at the shelter for the most chill cat they have. My youngest cat likes bunnies and taught them to do a running/chasing game with her, but if her personality were just a little different it wouldn’t be a game to her and she would hurt them. My third cat has no respect for rabbits and required extensive training for him to understand they are not to be hunted, and he is not even remotely friendly with them.