As an engineer and machinist, he makes a convincing case, especially when dealing with sound. He’s on to something but his conclusions seem just ‘stuck’ in there. Any sufficiently large explosion in a tightly confined space has the power to move any amount of rock - just depends what is used and how much of it. Dunn said one component was hydrogen gas - that would work.
I’m sure you don’t believe those pyramids were meant to be tombs ... so Dunn’s idea about their purpose is as good as the next, IMHO.
Yes, of course they were built to be tombs, the entire plateau is one big complex of tombs and burials, including the burial of the architect of the Great Pyramid, Hemiunu. I'm not sure when that doubt got started (I watched parts of the "In Search of..." linked above, it was in there 40 years ago) but it makes no sense at all.