I do not think you understand how much debris a person could be buried under. The house destroyed by the tornado I worked on, was a pile of rubble up to 6 feet deep. Even after a days worth of work by over a dozen people including two tractors we had only reduced on side of the house to about 2 feet deep while the other side was a good 3-4 feet with huge voids.
We have great technology that is really magic. Seeing a body buried under the 2-3 feet of debris would be very advanced magic I do not think we have. I do not know of any heat related technology that could see me through my roof. If the house collapse around me and buries me on lumber, insulation, wire, pipes, duct work, drywall. house hold goods, etc., it is even worse.
The reality is that the odds of anyone surviving a house reduced to a pile of rubble is pretty much zero.
The tornado site I worked had four homes hit by the storm. Three homes were destroyed and reduced to rubble. In those three homes, three people died. There was one home that was destroyed but structurally intact. The people in that house lived. If the house was reduced to debris, the people inside died. From talking to the responding VFD two of the people sounded like they died from crush injuries. One died because his leg was almost severed and I assume he bled out.