From what we know right now, Russia being behind this is just conspiracy theory. A bad conspiracy theory because it doesn't make any sense:

Let's say you want to make your geopolitical rival weaker. It makes sense to promote California separatism because they would lose a state that massively contributes to its economy (this is assuming that the news is accurate and not just US propaganda). It doesn't make any sense to promote Alberta separatism and give your enemy an extra free state, because that makes it stronger.

This is exactly what the US does when funding Radio Free Asia: it promotes separatist movements in China.