"I would ... call dog an instance of INameable"
That's fine, don't overthink it. Each instance of Pet is also an instance of INameable, that's the gist of inheritance. This kind of "replaceability" has also a name, it is called Liskov substitions principle.
Perhaps dog is also simply an "implementation" of INameable
No, that ...
Development, testing, acceptance and production
internal network vs perimeter