https://www.livescience.com/how-many-moon-meteorites

According to ballpark figures from this article, any given square kilometer of Moon-surface is hit by a small meteor about once every thousand years. Each of those small meteors delivers energy comparable to a ballpark of 3 kg of dynamite.

Over a million years, that comes out to a given square kilometer getting hit with a thousand impacts of 3kg of dynamite each.

The Great Pyramid is about 250m x 250m, so it's about 1/16 of a square kilometer, so let's say it gets about 50 impacts in a million years.

Here is a video of what happens to a fairly large concrete cube when you detonate "just" 2kg of dynamite on top of it (not inside or under, which would be more damaging; this is a decent simulation of how a meteor impact would work). It does not go well for the cube.

However, the Great Pyramid is much larger than said cube. It seems clear that any single one of those strikes would do significant visible damage but would not destroy the structure. 50 strikes shouldn't be enough to do that either - not if they're randomly distributed (as opposed to what we would do in, say, a controlled demolition). 500 (10 million years) seems like it would certainly be enough, however.

Caveat: these are ballpark estimates, and depend in large part on the estimate of meteor impacts and the effect of an impact on the material. I used concrete as an example, but solid stone would be more resilient, and something like a hardened, reinforced bunker with modern building materials would be even more resilient. This also doesn't take into account larger meteors, simply because we don't have a reliable estimate of their rate-per-year.