Does anybody know chapter and verse about whether it can be done as SNY (supernumerary) too?
I'm thinking about the situation where your PPL mate, who is acting as PIC (so you are just a passenger) is confident and gentle enough to let you handle the controls during take-off and landing.
Technically you are the "sole manipulator of the controls" so things should count, but since you have no crew function, nothing should go in your logbook - except possibly an SNY line.
Not in this example, you can either fly P1 with nobody else onboard or Pu/t with an instructor. You cannot do this with a PPL mate because while you are flying he/she is technically a passenger because he/she does not have the relevant qualifications to be otherwise.