I don’t use their cloud. I have no need. I use Orca slicer. All I would want on the phone would be to see the print progress. My esp32 camera does that - iirc it cost about £8.00. My x-plus, 2.5 screen with usb battery pack, gives me enough control, gives temperatures etc., more or less as good as the handy app - I think there is an i-phone version of something like the handy app that works in lan mode being developed.
wrt mqtt, I started from here MQTT for A1
My suggestions are so that you can use web cam and notifications in Lan mode.