Anki Cozmo [1] looks cool. Does anyone have any other suggestion about a programmable robot with wheels and a camera, either more "bare bones" (and cheaper) or one that has some extra features, like a arm that can grab stuff?
1. Build a DonkeyCar http://donkeycar.com -- you'll end up buying a servo controller board which you can use your pi to control any servos including those of a cheap robo arm.
2. Buy a Misty https://www.mistyrobotics.com -- more expensive but a very powerful personal robot computing platform
The Misty seems like it could patrol the interiors, not good enough yet but we're getting there.
Knightscope should start selling here: https://www.knightscope.com/
But a movable webcam with some other capabilities (audio probably) might be a better deterrent.
It's more expensive though.