Agreed.

Also, if you are running PiHole, HOPEFULLY you are also running a firewall. You should be able to easily block the IP address and / or domain at that level as well.

Of course the other option, as others have mentioned, is to get rid of the default gateway so it can't access the Internet to begin with.

If you are seeing it in PiHole, you can just block it in PiHole, that is part of the purpose behind it. Find it in the list and select block.

I usually ask for small devices like Pi's. I also am really getting into the maker space so things to help / explore that are on my list too.

"self hosted DNS server" is what I searched for, but I also knew what I was looking for "Unbound" with PiHole is what I use.

Also, Windows has a host file that it uses. %windir%\System32\Drivers\etc\hosts

%windir% is the environment variable for your windows install directory. Usually C:\Windows

You can add your entries in there, just like Linux, though I am sure the syntax might be slightly different. I really haven't played with host files on Linux, yet.