https://oag.ca.gov/firearms/travel
This has a lot of material not particularly relevant to the question but does give detail on what "loaded" or "unloaded" means in context here.
https://oag.ca.gov/sites/all/files/agweb/pdfs/firearms/pdf/cfl2016.pdf
"A firearm is deemed loaded when there is a live cartridge or shell in, or attached
in any manner to, the firearm, including, but not limited to, the firing chamber,
magazine, or clip thereof attached to the firearm . A muzzle-loading firearm is
deemed loaded when it is capped or primed and has a powder charge and ball or
shot in the barrel or cylinder . (Pen . Code, § 16840 .) "
So, a pistol case which holds a loaded magazine separated from the pistol would be suitable for transport of a handgun. Now you could lock that case, or carry that case in a locked container, like the trunk but not the glove box. Long guns (Noting that assault "weapons" and pistols have essentially the same transport requirements but you can't travel with an assault weapon to California). And a long gun could not have an side saddle or attached ammo sleeve of some sort, etc. Also, while the unloaded long gun might not be in a container in the vehicle, "open carry" is not legal so casing is required (under many situations) to carry between the vehicle and the destination.