The NPF rule is somewhat more "advanced" and more accurate than the 600 or 500 rule for astrophotography - both the latter tend to still produce star trails as camera resolution increased in recent years.
The NPF rule is
Shutter speed = (35* Aperture + 30* pixel pitch) / focal lenght
Shutter speed is in seconds, Aperture in f-Stops (you can just insert the value, e.g. 2.8 for f/2.8), pixel pitch (the distance between two pixels on the camera sensor) in µm and focal lenght in mm.
In the 500 or 600 rule, you have to multiply the focal lenghts by the crop factor of your camera (e.g. 1.5 for APS-C). For the NPF rule, I found no information whether this is necessary.
I assume it is not necessary because for a full frame camera with 24mp, the pixel pitch is larger than for a 24mp APS-C camera, which could possibly account for the crop factor.
So: Do I have to multiply the focal lenght by my camera's crop factor in the NPF rule?