Not without NJP.
A command does not need to impose NJP to impose a curfew on a US service member in the US. You can have a curfew imposed in training while in the US as per my original example. You can have liberty on a ship expire at a certain time even when in port in the US. Your command could tell everyone to come into the base or station and pitch a tent and that is where you will be sitting at 2000 tonight and where you will be living for the next week.
It is totally legal to do any of that in the US to US service members. It would be ill advised as morale certainly wouldn't improve but it is legal. I am only pointing out the falsehood of the comment that "You can't impose a curfew on US citizens on US soil. It isn't legal."
Remember you are in the military not your average citizen. Your CO could tell you to put a cot in your office and live there until xxx job is done. Again, probably not the best way to win friends and influence people, but it can be done legally.
But now to your average citizen. There are curfews imposed by cities on youth all over the country. They are US citizens on US soil. Professional sports teams have curfews. Again, they are US citizens on US soil.
I am certainly not supporting all of the curfews imposed but yes, a curfew can be imposed on US service members in the US without NJP.