I’ll happily acknowledge that you seem to know much more about this topic than I, so the following isn’t intended as a correction, merely the suppositions of a lay person.

The question is really subjective. What is a caveman and what is a pet and how does that relate to a domestic pet.

I’m sure there has been some kind of opportunistic co-operation since forever, even if it’s as simple as a wolf pack not attacking a group of hominids because they’re dangerous but also sooner or later they will kill something and leave a carcass.

At the other end of that spectrum is something like a modern service dog which is an extension of the capability of a hominid.

Somewhere in there you cross a threshold to be a “domestic pet” whatever that is.

Another aspect of what I’m saying is that even if domestic pets emerged there will be instances of remarkable pet-like behaviors stretching back much further.

As an aside, I didn’t really read the article you linked but one part, perhaps out of context, says:

domestication of the dog began in Siberia 26,000-19,700 years ago by Ancient North Eurasians