Well, you can get a 'cat toilet'. A lot of them are pretty terrible, but once you get around the mid-range price of 300-400, they mostly have all the kinks worked out, and you can install it to connect to sewage like a normal toilet.
The one downside is that pretty much all of them use plastic beads as the litter, and sanitize with heat. This means if anything malfuctions, then you get the smell of burning fecla matter and plastic.
The one downside is that pretty much all of them use plastic beads as the litter, and sanitize with heat. This means if anything malfuctions, then you get the smell of burning fecla matter and plastic.