Change voltage without consumption
a resistive divider is never an appropriate voltage regulator. It's dangerous – the voltage seen by the low voltage side depends 100% on the current it draws

The disadvantage is that the consumption over the remaining 5V - 3.3V = 1.7V is lost / wasted.

That's not even the point. You say this works, which means your resistors are using significantly more power than your 3.3V circuitry. This is a terrible design choice!
The voltage can be much higher or lower than the target current, unless you waste a lot of power through much too strong resistors; I hope you remember Ohm's law and how a loaded resistor divider is not the same as an unloaded one.
So, drop that really bad idea that everyone should tell you is a bad idea and use a linear voltage regulator. Done.
You get an actually regulated voltage, and don't waste as much power.

You could use a more expensive but more efficient buck converter instead of a linear voltage regulator, but &quot;5V arduino&quot; kind of implies &quot;not power efficient&quot; to begin with, so my guess (!) is that this won't save a significant amount of energy.
If you want to be more energy efficient, re-base your digital logic to run on a microcontroller off the same 3.3V (or lower) rail as your NRF chip, and supply both from a switch-mode power supply.