You can get a replock and swap it for the door locking barrel (not site how affective they are tho).
You can disable the diagnostic port too.
You can fit mechanical locks to the side and rear and controls.
Imo best security items are what you make and not mass produced generic items that thieves can do homework on.
Personally i think my rivet is enough to make them think, ah can't be arsed with that but if the van is left somewhere where would be thieves operate then you can only do your best.
First thing get rid of the drivers door lock/or disable it.
Above is based on the new connect being the same as the custom or mk8, I've not played with 1 or read much on them, i haven't read if they're any different tho
Personal my favorite is to hire a security guard, out of work actors are good.
https://youtu.be/H9_GlqRRs0s
56 350 2.2 130ps mk7 with 2 side doors
65 290 2.2 125ps custom with 2 side doors
07 350 170ps
Ids v86 licence + v86.04 update + xprog
hereIds map
here