If you REALLY need it, I’ve seen some people recommend ClamAV but really, I don’t like the concept of antiviruses. They run with I’m assuming full access to your storage and generally bog down your system performance. IMO, the best line of defense for your system is you. Use your common sense, stray clear of the shady websites, stick to well known and safe recommendations (especially relevant since you sail the high seas) and don’t run random commands from the internet.
I’m not sure another civizilation is possible on Earth within our lifetime. Look what we’re doing to the planet. Even if some species did evolve to become highly intelligent like our ancestors, humans would put them in a lab somewhere to study long before a civilization has a chance to develop.
I’d get the Pixel because of the long, not to mention timely software updates and security patches, better hardware and GrapheneOS. If you do get the Fairphone, use DivestOS. See this comparison