Hi,
The authoring UI does not allow you to replicate/activate smaller entities than pages/assets, but the API supports it.
I wouldn't give authors the chance to activate only certain components of a page, because a page has only 1 cq:lastReplicated property; and do you want to update this property for the complete page if you just replicated a component?
Also you would have to implement the complete UI plus the logic yourself.
Unless you have a very compelling reason to do it, I would not recommend such an implementation.
Jörg