Hi,
nice projet. I am very interested in it.
But why you are using 5 V and not 3.3 V? The ATmea328 works with 3.3 V too and the NRF have to use 3.3 V.
The only restriction on 3.3 V is the clock limitation for the Atmega (8 MHz). But with no crystal it don't care.
For example you could use an HLK-PM03 instead of HLK-PM01 and remove the linear voltage regulator. So you get more space an everything have the same voltage level.
And another point is, it is recommended to use a capacitor (0.1 µF) to ground for each voltage pin (Vcc, Avcc, Aref).
