There is no chance in hell we are dealing with TIE fighter size ships here lmao, or shuttles, or fighters, or anything that falls under the realm of "small."
Let's try paying attention to the text very carefully now:
There is no speculation to be had as to which objects are moving here, it is not the broken debris on the floor of the hangar, rather it is the intact vehicles described as giant phantoms. FYI: Nothing small can be classed as giant, maddeningly, this has to be spelt out.
Again it's the aforementioned vehicles that are moving here. The giant phantoms.
Now the author moves to describe "a cruiser", and in that respect we can't be sure it's one the aforementioned vehicles. Nonetheless it's size will quickly become apparent, for now pay attention to the fact it passed over them i.e. it was levitating, not simply being pushed.
Now we have the cruiser that just passed over them to hit the wall, smashing into pieces that rain down on them. Note that this isn't Dooku barraging them with some missles, they are falling from above - it's clearly the vehicle that was just destroyed.
More importantly? These pieces hit the ground with deafening crashes. Deafening is extremely loud by the way, which would only be the case if these pieces were large, and therefore part of a giant ship, not a tinny fighter. Moreover, these pieces are so large that Anakin and Obi-Wan have to leap and dive to avoid them, even resorting to Force deflection in some cases. Making it very clear that these pieces are both sizeable and numerous. Again, impossible to be the fallout of anything short of colossal.
Pay attention to what is happening here, "mountain of metal" is not just some liberal use of hyperbole, Dooku literally constructs a mass of metal large enough to fill the width and depth of the hangar in a way that blocked them in. Hint: this hangar is previously described as vast, vast enough to leave Anakin speechless, who has seen plenty of big hangars, Ferus says it could field an army, and it's also large enough to accommodate "gigantic" statues lining the length of it. Later Anakin climbs one of these statues, climbs because it's too big for him to leap atop of, and even when up the top of it, he still cannot see the ceiling.
So yes, we are dealing with a mountain in a much more literal sense, not the kind of you're going to make with anything remotely small, but g-i-a-n-t ships.
A final FYI: The fact that the planet is described as strong in the Force by the Jedi, but feeble 1,000 years prior by Bane is a discrepancy that can easily be explained by the different perspectives. The Jedi are unaccustomed to the dark side, so even a whiff of it might seem overpowering, the reality being that to an actual practitioner, the amp to be had off of Korriban was factually negligible by this point.
