Currently Virginia resident, can I buy an off-roster pistol before moving to California?

Title explains most of it. Assuming I'm legally carrying the correct amount of rounds, can I purchase a Glock 43X in Virginia and then move to California with it so it's off-roster? Furthermore, could I make an 80% polymer Glock and then bring it to California when I move? Or is the lack of serial number violating state law there? Thanks!