Currently, there is not a way for you to be notified. However, this feature is on our product roadmap.
After a customer triggers a factory reset, the router(s) will still show up under the Vilo Inventory and will show up as an offline network on the Wi-Fi Networks page. You can check the Operations Log to verify if the network was reset by the customer and use our Remote Configuration feature to re-set up the network for the customer. If the customer has access to the Vilo app, they are also able to re-install the network on their end and you will still be able to view and manage their network settings in the ISP portal.