I see. Didn't realise you wanted to create geo. You can make a CVEX Operator, place it in SHOP and then point to that code from the Vex Setup tab in an Attribute VOP in SOP's. A little hacky i know. You will end up with an asset inside an asset though.
I'm writing a bunch of tools in CVEX so I want to be able to have a node that gets updated everywhere, automatically. Also, attribwrangles don't let you declare structs I don't think, you have to go into the underlying vop