"retcon" is short for "retroactive continuity". You cannot seperate those two. Canon is official continuity, aka what the rightsholders, the producers, say. When they say it's prime universe, then in canon it is prime, per definition.
Everything else, like your personal headcanon, even (especially) fan fiction, books, comic books, Youtube videos, or if you personally don't "count" an episode or two, is in Trek all officially defined under the umbrella of "non-canon". You cannot use the official terms for that. "Non-canon" can, per definition, not have a "ret-con" or reboot.