Using a Nano as an extension to a flight controller

I have been looking, and all seem to be 3.3v, 1w.
I would have thought that 15w, 5A would be a better size.
What do you think?
what is the draw for a Zero?- I will check the specs.
it says 7-12v DC in.
The flight controller has a whole sub-board producing a regulated 5v.
Where could this be connected?