This one can have legal ramifications. Generally speaking, you can explicitly state that you are not willing to follow the law regarding the duty of jury members to make judgements of fact based on the facts presented. You should be able to defend your position, and you may be asked to do so privately.
If you were to potentially taint the jury pool by going on about nullification, that might open you up to contempt charges. I’m not saying that it should, but people interested in the subject should know that it’s a risk they run if they take that approach. Talking about nullification outside the context of a court falls under free speech, but I do think people have been cited for handing out nullification flyers outside of a court building.
I have a similar problem in that I do not believe free will exists, which shifts the idea of “guilt” from a moral to a medical dimension. I could not find anyone guilty of the crime of murder, for example, because there are a whole range of cause and effect cascades that brought the particular action about that had nothing to do with free will or choice. I do think it’s ethical to remove someone who has committed murder from society for as long as that tendency persists, but that’s a very different thing than finding someone guilty of the crime of murder, which requires mens rea - a state of mind that renders an individual as culpable for their actions. I would not find that the defendant had willfully carried out the act, any more than I’d find someone who had an epileptic seizure while driving and killed a pedestrian as guilty of murder. In order to do so, I’d require the prosecution to demonstrate a conclusive neurological argument proving the existence of free will.