You can still pick up any meshes with the plugin and it will still be considered in the grip array, the template just automates a bunch of the grip logic when picking up a grippable mesh because it implements the VRGripInterface.
Also yeah I do appear to have forgotten to place all of the grippables on the wiki, it will really just be a “Grippable objects” with a brief description but it should exist, i’ll add a page today.
Generational inheritance is a huge part of engine and game programming in general, I would suggest that you use it, but even if not, at least make an actor component that handles the logic for you and attach that to the base class. Something that abstracts the logic out of each separate object and into one place where it only has to be changed once when you make holster changes.