And among other ground that's broken by the series, is the first use of the holodeck in Once Upon A Planet.
Actually that was "The Practical Joker" (where it was just called the recreation room). "Once Upon a Planet" was a sequel to "Shore Leave," set on the amusement park planet; a holodeck would've been redundant.
Although that's another detail that was ignored by later productions, since early TNG treated holodecks, at least aboard starships, as a brand-new innovation. Then again, later series pretty much retconned that too, since VGR established that Janeway (who was the same age as Riker) had grown up with children's holoprograms, and ENT had the technology existing as far back as 2151.
Which just goes to show that canon and continuity are not the same thing; something can be part of the canon and still have parts of its continuity ignored. Canon just means the core body of work from the main creators, whether it's consistent with itself or not. TAS was executive-produced by Roddenberry and Fontana, with Roddenberry's Norway Productions as the co-producers with Filmation, and with Fontana as what we'd now call the showrunner, with Paramount distributing. I'd say that makes it from the main creators of the franchise.