AFAIK there is no counter to check a bag airside. You will have to go to the AF counters landside at 2F to check the bag on your flight to NCE.

But if you travel "heavy HBO", I would not bother myself and consider going directly to the gate then wait to see what happens at boarding. You may be allowed on AF to board with both a suitcase and a backpack (especially if the backpack can still be placed under the seat in front of you) without any concern. If the flight is full, they will be able (and ask) to check bags at the gate. If it happens, you will collect your suitcase at NCE as if it were checked the normal way.

Nonetheless, 2C-2F may not be the most convenient connection. Fingers crossed for you to land on time and make it hopefully!