How can I best prepare a nozzle for a gas cooktop so it doesn't lock into place?
High temp anti seize , auto parts stores carry this product type.
On the burner side of the gas valve there is no pressure so messing down stream of the valve is not a problem.
The stuff I use at work has copper in the name but it is a paste with the consistency of tooth paste doesn’t take much.  Just make sure it is high temp.