As long as the plastic-lined nipple is of the type called FE, for fitted end, where the plastic liner covers the lip of the steel nipple, that is superior to brass because it won’t react with water heater steel.
As to the anode, it wouldn’t be consumed so quickly. You’ll find it under a plastic cap, most likely about halfway between the edge and the center of the top.
Mr. Hype (aka Randy Schuyler);)