I and many people I know swear by the litter robot. Off the top of my head I can think of 5 different households in my social circle with 1 or more litter robots.

For 4 cats you might want two litter robots as they tend to fill up quickly with multiple cats. Or set up the litter robot in addition to a traditional litter box so the cats can choose where to poop.

Maybe I'm being the overly marketed to weirdo here, but this is the third post today asking about cat box solutions and the comments on all of them are pushing the Litter Robot 4. The timing is pretty weird... again is it just me?

I wouldn't look at HA first for this kind of thing. Asking a cat group would be more effective unless you're looking to add smarts to a dumb litter box.

Others have already mentioned the litter robot, but one automation you might find handy is having HA trigger a robot vacuum to go vacuum the room where the litter boxes are, after it detects a cat using it. It'd help keep litter off the floor if your cats like kicking it out of the boxes.

Also if you're having to clean litter boxes multiple times a day, how many do you have? Iirc the general rule is one litter box for each cat plus one extra, so for 4 cats you should ideally have 5 litter boxes.

I've had both the CatGenie and the Litter Robot 4. While the novelty of a washable cat litter made the CatGenie appealing and I used it with my two cats for a few years, it was just prone to not collecting all of the droppings and then air drying it, smelling up the whole house. Cleaning it was also a huge and disgusting pain in the ass when it got clogged up.

The Litter Robot 4 is significantly better. It's quiet, easy to refill, cycles quickly, and with the newer firmwares being put out, is less prone to false positives with its sensors. The only iffy thing is still the full Litter drawing sensor saying the drawer is more full than it really is, but it's a minor annoyance.