Yes it can be done. And was done. Later, by the Romans and more in the Middle Ages. But not then. Not by pyramid builders.
What that might constrain is the shape of the hollow that could be safely made. Go for a straight contour and it might fall apart. A curved contour and the pressure would be equalized.
Again I don’t say this by way of claiming that these pyramid ideas HAD to be right, only by way of trying to honestly investigate whether and how it could have happened, boosted by means of a divine insight.
The bible itself is powerful evidence that at least significant quantities of grain were kept in cities and we know of no city pyramids today. A pyramid theory would have to posit pyramids that are now demolished or disassembled. Something for future SDA or SDA-curious archaeologists to discuss.