What is the best way to get PCS approval, and to get any update through the right method, e.g. what is their channel for them?The reality with any BIOS flash is that it can fully brick your motherboard so you can't boot.
Doing it with PCS approval immediately covers you if something should go wrong, so in the very worst case, if the board did brick (which is highly unlikely these days), PCS would just swap it out.