Most people advice against running metal based data cables even over short distances outside because if lightning hits nearby it can induce enough current in the wires to destroy connected devices.

So if you're going to hand dig and put down any type of cable then it should be fiber. Here is an example I found from a quick search just now showing you that it's not that expensive: https://www.amazon.com/Jeirdus-Outdoor-Armored-Singlemode-100Meters/dp/B07VVPGDFH/