Just depends on the exact set up. There are ups which allow for an orderly shut down and a timed restart. So the Z wave switch cuts the power to the ups, the ups switches the battery for however long you have the setting, ups shuts itself down, the ups turns itself back on. That process reboots the hub. Then the hub turns the zwave switch back on, UPS is back on mains.
But different ups have different features.
There are also nonnetworked devices which just reboot themselves periodically on a time schedule, and that might be an option. I know there are some community members using those. So that can be a simpler solution but I’m not sure how the two prong issue fits in.