Well, that all depends on how important you think various things are. Imagine how confused the Thermians would be at what Discovery did. There are some of us for whom the visual are as much a part of canon as the dialog. So redesigning the TOS Enterprise automatically boots it out of the main canon and a parallel universe is the only explanation.
As I pointed out before, there is a long history of fans establishing what their canon is that includes or excludes things. As far as I'm concerned, the only productions since Enterprise that are part of the main continuity/canon/timeline are Picard and Below Decks. I haven't decided about Prodigy yet.
And the subject of canon goes back to book series. The original canon are the stories created by the original author. If another author picks up and continues, they may have a lot of fans, but canon? That is up to the fans. I can think of several authors whose series have been continued after their passing and I would not consider those continuations, however authorized by the author's estate, to be part of the canon. The same with Star Trek. While they were Paramount (1966-2005) there was a solid continuity that grew. When CBS got involved that went out the window.