The receiver is the part of the gun with a serial number that has to be reported to the government when sold or transferred. Every other part and ammunition are normal goods with few restrictions.
Only one part needs to be self crafted to make and fire a ghost gun. They are not impossible to detect through investigation or forensics, they're just unregistered.
California accepted a petition for an initiative to put a secession resolution on the ballot. The state of California agreed that the paperwork submitted was valid and so they are approved to start collecting signatures.
No one in the California government is seriously discussing secession as far as I'm aware.