I agree that Cora wants power, but power over WHAT exactly??
Does she want to control/rule FTL? SB? All the realms? If her goal is to become the Dark One, then why? Rumple became the Dark One to protect Bae, but if that’s her goal then what does she intend to do with it?
I think she just wants to be the most powerful so that no one can interfere with her when she wants something at any given time…at least from my perspective that seems to be the way they’ve painted her. When we see her backstory my perspective may change.