Aside from update frequency you wouldn't, users can't tell the difference if it's done well. Are we not talking about "the state of software development"?
What are some well done cross platform apps that don't unnecessarily drain battery life? I can think of one - VSCode.
You're talking about Electron there, which like phonegap is a browser wrapper and a different thing to RN. I don't believe RN is known to be a battery drain in general.