I wouldn't go so far as to say Snowden is a secret Russian/Chinese agent but what do we know?
We know a lot.
We know if he was anything remotely like a secret spy he would have given some or all of the data to them in secret and cashed in. The only way we'd ever know about him is if he'd got caught. Snowden didn't get caught. He's a fucking obvious whistleblower and a hero.
This is the factor that many of his dense detractors completely ignore. If his goal was to be a spy of any sort against the USA, he would have done it in secret and would have been financially set for life instead of a target of the military-industrial complex.
What we know is he's a hero who knowingly put his ass on the line for society (even for the ingrates).
If you've got conspiracy theories beyond the most obvious, then please spare me while I point you to this: