apolonio:
I have relays, but the PIR wont be able to turn them on. Part of this for me is to learn more about transistors, I thought a transistor would be more appropriate in this case.
It's fine. Although I missed that in your drawing the supply was connected to the RAW pin. I wouldn't count on the Pro Mini's onboard regulator working very well on 6V, especially as the battery ages. So connect the supply to the Pro Mini's Vcc pin instead. A MOSFET will also work fine, but I think has very little advantage in this case (and will be the more expensive option). Collector-emitter saturation voltage for a 2N2222 shouldn't exceed 200mV until collector current gets above around 250mA, which it shouldn't unless the Nordic radio module draws a lot more than I think (I didn't look it up).