Avoid the Pro model, there is no added benefit of opting for a the 'smart' Pro version of the Eversweet 3. Get one of their cheaper non-smart options.
To access the water fountain on their app, you need to either use Bluetooth locally, or via Wifi connect through a compatible Petkit product that has Wifi. It means your options of remote control are very limited unless you have other compatible devices from Petkit.
As there is no level indicator on the side of the device, you rely on a small LED at the bottom of the device to tell you when it needs to be refilled with water. The most important feature of a smart device I would say is the ability to notify you on your phone when the water level is low, but the water fountain has no ability to do so. Until that is fixed, do not buy this product and get something cheaper.