A conspiracy theory that is more plausible is that the virus was circulating during the World Military Games in China in October 2020, pushing the timeline back by weeks, not months and years.
But, again, I have to consider it a conspiracy theory because so many athletes got sick, and got tested. It would be way to easy for any single one of the 100+ sick people to have taken an antibody test early in the pandemic (I'm sure many have done so, and it came back negative).
As to why the governments of Canada and the USA refuse to look into the possibility and rule it out is interesting though. They have the samples, at least some of them, and they are allowing conspiracy theories to fester. It's kind of the opposite of what they claim to be doing.