This is definitely STEMamazing! How can you tell if there are hidden cavities in a pyramid if you don’t want to drill or dig holes? First, place detectors in the base of the entrances you do have and wait for muons to bust through. Muons are cosmic rays from space that have broken down into tiny, high energy particles that can travel through rock. More can get through if there are air pockets in the rock. Then, with some clever geometry and mathematics, the pattern of the muons detected can draw the places where there are holes in the pyramid. The next question is, what are in those holes?
See where they found the hidden cavity at: https://sciworthy.com/new-cavity-discovered-in-the-great-pyramid-of-egypt/