A robot vacuum is small and light, but it comes with a charging dock that has to travel with it and, on smart models, saved maps that are worth preserving before you unplug everything.
Pro tip: Charge the robot to around 50 percent before a long move rather than fully draining or fully charging it, which is healthier for the battery during storage.
Watch out: Do not let a robot vacuum's battery sit fully depleted for an extended period during a long move or storage, since deeply discharged lithium batteries can degrade faster.