People have purchased ammunition etc., and things needed to legally make guns for their own use, and transported them to California.
Who knows what will happen if the laws become more extreme. Also who knows what is happening outside the legal channels. It is still a relevant development.
Yes, that’s legal. You can still buy ammo in other states. You can still buy gun parts in other states, except for the serial numbered receiver, which needs a California FFL to transfer.
Ammo and parts, you can buy all day, but not guns. That is not legal.