I have the same request for this update. I have a raspberry Pi zero W and PFXMini that are as much use as a chocolate fireguard right now.
If the ERLE website had said " compatible with raspberry pi zero, but not the W version" I wouldn't have spent the last 2 evenings reflashing the supplied SD card then swapping between SD cards, OS's and a spare PI 2 to identify that it's the OS/zero W compatibility that is the issue.
Seriously though, even after looking again I couldn't find this note and it would save other customers a lot of confusion and frustration in the interim.
Do you have a timescale for the new OS release that I can plan to, as my project depends on Wifi capability?