If you want to visit another pier, you should ask the security agent to visit a shop in that pier.
However, I am not sure the AF dragon at the lounge would let you in considering your flight is departing in another pier.

Frankly, even if 2E-K and 2E-M lounges are significantly better in terms of catering, I would not bother clearing security just for that matter and asking to pass again landside (which is not something easy when you are departing airside - you won't find any connection signage and need to ask a security agent to go through the security gate backwards which is something really strange).