Not yet you don't, but it's getting close. Open rebellion would consist of a state government resisting the federal government by force of arms. If the federal government attempted the arrest of a few mayors, and the state authorities fought back in a gun battle, then you could claim open rebellion.
Right now, it's more like a quiet rebellion.
Would resisting by force of arms be construed as arresting or shooting at ICE officers? I would not be surprised to see that coming.