In the US it is possible I think for an instructor to instruct for a higher rating and certainly to conduct a BFR without a medical provided the instructee is entitled to be P1 (and obviously they must be P1 in this case).
For myself I would not be overly comfortable with that. Since I am logging my time to renew my EASA rating (with a 61.75 on top) I always record the way I was taught as PU/T and I agree that in advance with my instructor. In the UK I take that as read.
High time / frequent flyer pilots may feel differently but I would always expect to defer to an instructor and subconsciously at least give up some P1 duties in favour of demonstrating competence (which let's face it usually means competence in manipulating the controls).