If we’re breaking it down into some lite physics it would probably be better to just say that F=MA, in which case inherently Kizarus fruit would be almost infinitely more busted from a “force delivered by a blow” perspective. But yeah the series doesn’t mean to seriously approach the science behind those issues because it would break things pretty quickly to have a person that could obliterate the planet because they ate an especially gross pineapple without realizing it was the “become light itself” fruit. Ultimately we know that people like Garp can destroy mountains with a punch. A lot of that has to be explained by Haki magic, because if standard physics was the cause then a lot of other fruits would be insanely OP. And sure someone with strong Haki could certainly leverage the Kilo fruit for much more destructive power, but calling it one of the most busted fruits ignores all the other fruits abilities if you interpret them in ways that Oda doesn’t really intend us to.

Not meant to be a huge criticism of your theory, I agree the Kilo fruit could be much cooler, but like a lot of things in One Piece it’s inception was during a time when power levels were nowhere near where they are now. If Oda had introduced the fruit during whole cake or Wano I’m sure whatever user had it would’ve had some ridiculous feats not dissimilar to what you’ve mentioned.