In the US, the US has the right to classify anything however they legally like.
PoW, because it doesn't clearly show who the traders are, is a private operation.
Because you might be able to figure out who the traders are in PoS, it might fall under some US heading.
But the way to get out of almost all the US regulation is, build into every client or core client, that the use of this client or app is private. Literally place a privacy agreement and notice into the client, that you have to pass through to use the client.
If you want to do a deal in cash, and the other dealer is right with you, and you do it privately, it isn't public. It doesn't fall under public laws. To make it clear that it is private, sign a proper contract/agreement to that effect. But at least, regarding crypto, have the statement built into the client or app, that every usage is private between the controllers of the particular addresses involved.
Why is this protection from government? For the same reason that what you do in your bedroom is private. Government sometimes gets away with invading your privacy, but it's because you don't know how to defend it in court.
Art I, S 10, C 1.5 in the US Constitution is known as the
"Contract Clause." The part that we are concerned with is this: "No State shall ... pass any ... Law impairing the Obligation of Contracts..." "State" includes the US government. If you have a contract built right into the client, you have exercised a contract right there, and there are only a few ways government can legally get around your privacy. But, if you don't fight it properly, government can do anything they want.
Contact an attorney before you try to use any of this. And be careful when you sign up as a 'client' of an attorney... because this throws you into having limited rights in court. The judge is the attorney's boss, and he might not agree with the attorney, or with you.
EDIT: Search in DuckDuckGo and Youtube on 'Private Membership Association'.