This is the correct way, only cellular should be disabled now. If it does not, then that is a bug.
You can go to flight mode via connman like this Code: dbus-send --system --type=method_call --print-reply --dest=net.connman / net.connman.Manager.SetProperty string:"OfflineMode" variant:boolean:true
dbus-send --system --type=method_call --print-reply --dest=net.connman / net.connman.Manager.SetProperty string:"OfflineMode" variant:boolean:true
dbus-send --system --type=method_call --print-reply --dest=net.connman /net/connman/technology/wifi net.connman.Technology.SetProperty string:"Powered" variant:boolean:true