Note that there are several different variants of Schneider PowerTags (with newer and older generations too) so it could be that they do not all use the exact same Zigbee protocol specifications, and not really sure why a such PowerTag would use ZGP (Zigbee Green Power) when they are all mains-power so are always powered.
FYI, as mentioned ZHA (and zigpy) do not yet support any ZGP (Zigbee Green Power) based devices but it probably will sooner or latet in the future: