Just get the MAGBLOCKS.

Quote
The manufacture, possession, sale, barter, trade, gift, transfer, or acquisition of detachable
ammunition magazines with a capacity in excess of ten rounds which are designed for or
capable of use with a pistol is prohibited.  This subsection shall not apply to magazines
originally designed to accept more than ten rounds of ammunition which have been modified to
accept no more than ten rounds and which are not capable of being readily restored to a capacity
of more than ten rounds.

And there is no definition of readily.... Me, I would just epoxy the magblock to the floorplate and call it good. With it epoxied, there is no way of using the magazine without it. You would have to use a whole new floorplate to restore it to 33 round capacity. When leaving the island with the firearm, I used these and they are "supposed to be installed by a professional gunsmith"..... Mine were for M&P so had the new floorplate included.
$20 on eBay https://www.ebay.com/itm/231785017808?epid=1317917634&hash=item35f776b1d0:g:negAAOSwHnFVuTQ-


   

When I bought an XDM from a local gun store it came with blocked mags because Springfield didn’t issue 10 round mags with it as it didn’t make the California approved list.
Upon disassembly it was just a piece of plexiglass glass that fit inside the spring and was epoxied to the follower.
DIY to block my additional mags I purchased off the internet.
They also sell aftermarket blocks that can be epoxied to the follower.
If you go back to a free 2A state just replace the follower.