There's several things stopping you here.

First off, you as the defendant do not just talk to the jury. You answer questions posed by one of the lawyers - you're not given a forum (at least, only very rarely) to simply speak your mind.

Second, jury nullification is not an "outcome" in the sense that it's a verdict or conclusion. It's a term to describe a jury ignoring the law(s) that is relevant to the case before them when deciding the verdict. So what you'd actually be suggesting to the jury is "Ignore this law that the prosecution says I broke". That's trying to get the jury to ignore facts, which could, as derspiny points out, get you either a mistrial, charges, or both. You can't just tell the jury to ignore facts you don't like.