This might sounds crazy, but I somehow calculated the AP for the bullet not using KE but using google earth. So I marked about 5400km of landmass/mountains that the bullet completely obliterated through it's way (take into account the height the bullet is flying at too), assumed that the destruction is as the same shape as the hole in the buildings (which diameter is about 27m, using 4.3m stories to calc), then look for all terrains that the bullet obliterated and found out it's mostly rock, assume that the bullet vaporize everything on it's way because it's not realistic for a bullet that could only pulverize mountains to reach it's destination 29000km away while obliterating 5400km of rocks on it's way anyways, and also due to extreme speed which will generate more than enough pressure to reach vaporization point, at least for half of it's way, plus I removed collateral damage out of the equation already (in short, me lazy). The height the bullet is flying at is also calculated using the 2nd shot (because while it was shot from around the same height as the statue, the bullet both times visually fly closer to the sea than it should if it stays the same height as when it was shot), which is about 10m or so.
And all that gave me around 19 Gigatons of TNT. Man, Island level Chainsaw man is here guys, and that's with the assumption that the bullet won't just also obliterate all the landmass and not just only dig a small hole through them. I don't even know why I did this when the hair calc is still there (maybe as a safeguard), and I don't even know if this is even valid or not.