Raspberry PI power supply switched with FET
Here.

Throws the manual across the room

Edit:
You cannot control an NFET on the high side of a load with 3.3V. The ON-ness is controlled by Vgs, which would need to be 5V+Vgs-sat, which is like 8-10V if this is a logic level FET.

I can't see a reason you need the blocking action of the FET here, unless you have a circumstance where the Raspberry Pi is getting power from somewhere else. You can slap that circuit in series with the PFET switch if it works, or get creative and combine them which I think is possible.