IoT laser cat toy that says, "would you like to play with the laser pointer" to a cat when no one is around, listens to the cat's response,or views it's body language, then activates the laser pointer toy on software interpreted interest could be a popular IoT appliance. [link]
Medically inert batteries
(Ag Zn) could power Dog bones that vibrate and leap into the air [link] from all-edible polymer motors (edible motors are published) when the dog replies to the smart speaker when people are away. People are likely to be less concerned that their pets have no privacy if interacting with a computer makes the pets happier, or, in some cases can actually distract from a destructive behavior with a goodie (all positive reinforcement for pets).
"use the catbox", "stop chewing", "quiet barking" in the pet's human's voice could be used during the day while people were away and the pets would be more likely to respond functionally when the human said it.
Going a little farther with the Technology I think ThZ sensors/lasers can see through fur, and the IoT pet toys or other items, like perhaps a ceiling mounted smoke-alarm form or combo could do simple veterinary diagnoses as well. They might be able to catch things early and then correlate having the veterinary IoT toy with actual longer pet life.
They could even do a little study that says a word or makes a tone, or displays a thing, or even activates an odor (IoT air freshener) when the person who lives with the pet is say 5,10,15,30 minutes away alerting the pet the human is about to appear to see if this prepares the pet, causing it to be more loving, or at its option, since it is a pet, more aloof!