My pocket got a few upgrades today, including the second revision RCORE with the Intel wifi on the headphone board.
Firstly, when it comes to swapping over the Firefly SoM, first make sure you’ve done the ribbon cable to go to the wifi board before you fit the SoM into the mezzanine connector or you’ll end up having to fit it twice - ask me how I know! To remove the board from the original carrier, slowly work around each corner gently prying it up, going round in a circle. Eventually it’ll come off. Be firm but gentle. Moving it to the new carrier is as simple as gently pushing it into place - I’d do this before you fit the carrier into the mobo.
The other thing is that you’ll need to install firmware-iwlwifi and reboot for wifi and bluetooth to work.
You can verify that the connection is solid by using lspci - if your intel wifi shows up, you’re good.