Archlinux - missing firmware for wifi adapter

[cypresstwist]

See this post I put up yesterday or the day before. I see all the links you refered to mention the 43456 version of the drivers. The problem seems to be that the WiFi chipset version in SOME of the new Pinebook Pros is 43455 and not 43456. The system tries to load drivers for brcmfmac43456 and that's why you get that error. You need the brcmfmac43456 drivers (attached in that post). Copy the three files in /lib/firmware/brcm/ then reboot. Should work after that.
I had the same error as you in dmesg and my 5GHz networks didn't show up (although 2.4GHz worked fine). The 43455 drivers fixed this.