I know a fair amount about this. Cold fusion is a fraud. It started out as experimental error resulting in seeing a non-existent anomaly. Then the theorists got involved who cooked up all kinds of cockamamie explanations for why cold fusion is a thing. Unable to get any of this published in respected peer-reviewed scientific journals they then went off and created their own journals that they peer-reviewed themselves. If you think Signal is a secure app then I would invest in this. Otherwise I would keep my powder dry.
My understanding is that cold fusion is just a low temperature and slower process than hot fusion. It would be appropriate for some applications, but not all applications.