-
It's about 18x14x10 cm.
It would look fairly obvious but I always thought that was the main point of a security camera? The recording is frequently of no use after the event and they aren't often monitored.
Apparently this fake camera has enough space inside for a Pi Zero and camera but it might require some effort to mount the camera - https://www.amazon.co.uk/WALI-Surveillance-Security-Outdoor-Warning/dp/B06Y4FJD33/
Cheers but I'm not sure how obvious that would look attached to the side of a house, it doesn't seem to give dimensions anywhere but I suspect it is largish as it fits a battery pack too.