In the granola state (California nothing but fruits nuts and flakes) it must by Cali law be from an FFL to an FFL coming into the state. Thus why lots of ads state no Cali sales.
If an FFL wants to not accept private ownership out of state transfer well it is their right to do so. No illegal sale for them if they did but a decision not to as a business model or like stated got burned somehow before. Their house their rules. Mine will except them and 15 dollars to do so. Anderson based. Let me know if you need one transferee.
CA does not require incoming transfers to be from an FFL:
https://oag.ca.gov/firearms/cflcfaqs#2