I do something like this in all my projects now. Except that I don't use example.com, I just use the name of the project. So if I'm working on a program called Frobnicator, I'll just have `module Frobnicator;` in my go.mod and do things like `import "Frobnicator/lib/blah"` in my source files. It works really well to be honest for non-library software.

But it's something you have to do as an active choice; the tooling, and your colleagues, will nudge you towards using URLs to your primary git host's web front-end. And it naturally doesn't work for libraries.