After some advice on lounge access for an upcoming trip.

I'm OW Emerald and will be at PVG and NRT airports. Travel is in Y but on China Eastern Airlines.

In Shanghai there is a CX lounge, but I'm on MU from PVG-NRT. May I enter a CX lounge when not traveling OW that day? This can be done with QF lounges (access any time for QF Platinum).

Likewise on the return to Shanghai can I use the lounge in Tokyo? In the latter case I am connecting to a QF flight number in PVG.