This is exactly how it works in the UK too in most petrol stations.

I assume it’s meant to be obvious lol

I’m using Ubiquiti at home (a switch and an access point) and self host the controller too.

You can disable automatic updates in the controller and then upgrade the firmware when you please.

Regarding if Ubiquiti have access to our hardware a cloud account is optional so you can just use a local login to your controller instead.