You know... books are only as "canon" as you want them to be. They ain't official. Like in my case, I accept only certain novels/comics/etc to be canon (as in, I like to think this really happened in the ST universe) in my personal view so long as they meet certain criteria.
Couple of clarifications as you have a few words mixed up. Which is understandable as most people who first venture here have these misconceptions.
Every location in your post where you used the word "canon" should be replaced with the word "continuity." Canon is not the same thing as continuity. The books are not canon regardless of who may or may not want them to be. Saying that would be akin to saying "Elephants are as much amphibians as you want them to be." It's factually incorrect. Similarly the word "canon" does not mean "official." Because the published novels
are official. They are officially licensed fiction that have to be approved and vetted by CBS/Paramount. To continue my last analogy, "Elephants aren't animals" is factually incorrect. And to use the same analogy for continuity "All elephants live in a zoo" well that's not necessarily true, it's possible but we know from outside sources it isn't true at the moment.
the simple definition of those words are as follows:
Canon: The source material created by the creator/owner of the property. In this case that is all live action tv and movies because those are the only things created by CBS/Paramount. Those aren't even necessarily in continuity with each other.
Continuity: Any material that does not contradict the events of other material. So even Fan Fiction can be continuous with screen Trek and thus apart of continuity.
Official: Any material that is approved and sanctioned by and the owner of the property. So in this case that would include the published novels, magazines, comics, toys and even Christmas ornaments, but not fan-fiction.
In conclusion not all TV episodes are necessarily in the same continuity, but all are canon and official. Not all novels are in the same continuity, none are canon, but all are official. No fan fiction is canon nor official, but some can indeed be in the same continuity.