They also allow SAA soldiers into Rojava and ship oil to the SAA. Once again they're playing both sides, likely as insurance against the other. If they were agents of the US they wouldn't be working so closely with America's enemies, and they wouldn't be directly fighting a NATO member. I think its fair to criticize them for opportunism, but that isn't the same as being a "US puppet" or whatever, since their actions clearly indicate an independent agenda which is not hostile to Syria in and of itself.
>by unilaterally declaring themselves a separate federation from the rest of Syria
They didn't do this. They declared autonomy, not independence.
>by destroying cities with American artillery
I'll ask again, do you think Assad hasn't destroyed any cities over the course of the war? Take a look at Aleppo. War brings destruction.
You mean the ones that were repressed and outlawed for decades and are only allowed to exist because they are controlled opposition?