Yes, I’m in a wheelchair with limited hand function and have a professionally trained service dog. It’s amazing what dogs can learn! He’s very good at buttons and switches, but a big dog’s nose is wider than a person’s finger, and the form factor has to be just right. It’s basically like a person pushing a button with their elbow.
We’re using the smartenit 3 toggle switch since neither of us can use a mini mote, but precision was tricky, so we ended up programming all three buttons to do exactly the same thing so it doesn’t matter where he hits it.
I quite often put a single button switch down lower on the wall below a regular switch. That way I can use my wheelchair or my elbow, and the dog can use his nose.
So the new Iris button, which is battery-operated, might be perfect for our needs. We’ll just have to see how hard it is to press. 
people with pet dogs might have uses as well. Imagine a button on the wall that your dog could press to turn on the yard lights when he went out. Or a button that that sets off a buzzer when he wants to come back in. Or starts a light blinking so he can tell you his water bowl is empty.
Obviously these all take training, but the first step is a button with a form factor that the dog can use easily. 