How to find and look in my firewall logs in macOS High Sierra

The IP Address that is visible to the websites you visit is your Router IP address. Since your computer is behind the router, you are already getting the protection from anyone being able to access your computer through a network, unless you specifically allow port forwarding from your router to your computer.

https://eshop.macsales.com/blog/34677-tech-tip-how-to-view-the-os-x-firewall-log/

Mine is empty but I know that my router's firewall is blocking several sniffs per second.

Which probably means any attempts are getting taken down before they even reach you. As I said, my router shows hundreds. One every few seconds for years on end.