Hey. I am new to this forum ( I, too, drive a Nissan Rogue) and one of the things that boil my blood is any rattles and creaks that go on in my car. I also have this seatbelt creaking issue and I finally found out where its coming from. I hope this helps.
This is the Driver seatbelt buckle:

This is the Passenger seatbelt buckle:
The reason why the passenger buckle doesn't creak(or shouldnt creak) is because they have that elastic band that holds it back from the contact point. For manufacturing reasons, the driver seatbelt buckle doesnt come with this elastic band. So the creaking actually comes from metal to metal contact (circled in red):
I just put some electrical tape on it so that it the metals dont come in contact (this is just a temporary fix):
I have tried it for a day, and the tape only reduces most of the noise. I have yet to find something that makes it completely silent. I am pretty sure the noise is coming from those 2 metal pieces rubbing together. Please correct me if I am wrong.