What PCB Plating do I need to use Exposed Copper Pads with Pogo Pins?
I work in the semiconductor test industry.  We've designed large boards, 40 layers, sometimes more. And typical pcbs too. We make a connection from our lager pcb to a probe card using pogo pins. These connection like yours are in the thousands..  Even 10k..   Because of the forces involved and the number of pogo pins making the connection.  We use a selective hard gold plating, exactly: Minimum 30 micro inches gold over 150 micro inches nickel. With very good results over the years. Hope that helps..