Actually, fallen Angel technology. God does miracles, Angels use technologies ... and there are good Angels and Bad angels. Demons are the disembodied spirits of the Nephilim. Demons seek a 4D physical living body to inhabit. The greys may be fallen angel technology of ‘biologically grown living tissue bodies which demons can inveigle to serve the fallen angels.
For many years, I was confused about fallen angels and demons. Now, I am pretty much convinced, that you are right. Fallen angels and demons are, what is described in Ephesians 6, as spiritual wickedness, in high places. In the Olivet discourse, Jesus said, take heed that no one deceive you. Unfortunately, judging from what is going on in the world, the wicked entities, have been largely successful in their deception. Many of us, however, are NOT deceived.