As qt5-qtsysteminfo will be removed I did some tests with nemo-qml-plugin-systemsettings as @flypig suggested here Sailfish Community News, 21st April, Sailfish SDK 3.9 - #10 by flypig.
I am under the impression that not all parameters in deviceInfo are set. I was looking for imei info (imeiNumbers, which looks undefined), but the same goes for something like wlanMacAddress.
The strange thing is that aboutSettings.wlanMacAddress works from systemsettings, but deviceInfo.wlanMacAddress is undefined at the same time.
deviceInfo.manufacturer is one of the values that is properly set btw.
What am I missing?