My Shiba very clearly is plotting to overthrow the government. Very externally visible inner monologue.

I think dogs are usually more "in the moment" than a human would be, but they're able to imagine future scenarios and then choose the course of action that they expect will bring about the scenario they prefer rather than the most immediately gratifying course of action. In other words, they do sometimes "stop and think" rather than just acting on urges, although of course they don't think in words. I'll go even further and say that some dogs have better impulse control than some humans.

I even met a dog who appeared capable of the sort of regret about past actions that I would call "guilt". His owner and I were returning from a trip and when I opened the house door, he was agitated and blocked my way in (he's a big dog) while holding an empty plastic bag in his mouth. I went back to his owner and she was familiar with this behavior. Apparently the dog had given in to his urges and eaten a bag of bread while we were away, and now he was confessing. His owner told him to go to his time-out corner and he immediately did while appearing relieved.

There have been people who grew up without language, and learned to speak much later in life. It can happen to deaf people who grow up in a place where they don't receive support for their deafness, for example.

But anyways, it is possible to ask those people what they thought about before they learned language, and at least one of them answered that they didn't really think about anything.

So if humans are like this without language, it's more likely that dogs are similar to what you suggest.