I have a cat who is excellent. So excellent someone would grab him from the street if they saw him. Or he would get run over because he is too relaxed around hazards. I can not let him outside in Los Angeles. I was able to get a kind of chicken coop on Amazon that has been converted for cat use for only $200. It’s large enough for me to stand up in. There’s no way for a cat to get into it on its own but I recommend getting a piece of wood from Home Depot cut to the width of your window, and the height of a cat door. Then you can put a cat door where your window is, like an air conditioner would go, and put the catio on the other side. Now put the litter box in the catio, and you have an enviable cat situation that makes dogs suddenly seem completely unreasonable.