@Lighthouse812, I use Andisearch as main search engine, which is for sure the most étical and private AI out there. But in general there are very few AI apps that can be used as a function in Vivaldi, starting with the privacy requirements and that are OpenSource (most are from Google, Microsoft or Facebook (Perplexity). Although OpenSource (except Perplexity) with some TOS and PP quite debatable.
It is still the best to look at Future Tools, Futurepedia or Hugging Face apps to use them occasionally if necessary, instead of an inbuild AI with a certain function which may help or not.