You can create virtual devices of various types and then they appear on the iHost and in Casts, but they tend to be only pre-existing device types. So for instance if you had a light sensor that used MQTT you could make a pretend Temperature sensor on the iHost until they make one themselves.
Here’s an official video on how to create virtual sensors, but the video is just a basic device. Making other sensors is a bit of trial and error. The key bit is to give each device a unique identifier (UUID) using
My guess is that a pretend power one will be relatively easy but I’ve never made one.