It is not "just as much a problem in the US". China's treatment of dissidents is far, far worse than the US's. It's not even close. Every reputable political ranking organization, from Freedom House to The Economist, confirms this.
Are you planning to be equivalent in notoriety/influence as Martin Luther King Jr? If not, the motivation/incentives for domestic law enforcement to target you aren’t really there. It would be a waste of their time and finite resources.
The PRC has a bit different motivations/incentives and theirs are not aligned with a perceived U.S. national security interest.
Whether you and I agree with the US national security apparatus's mission, in my opinion, it is at least more oriented towards safeguarding/promoting the US’ self-interest.
That’s not to say I agree with all of its actions, just trying to explain what I mean when I say there is difference in motivations and incentives.
This is just as much a problem in the US.