Can I set up alerts for certain devices?

That is a great question. At this time and after some research I am not locating anything that you can set up to get a notification other than forgetting the device. If you want you can use the link: https://comca.st/3GpP5cZ to help personalize and control your home network by pausing and un-pausing devices when you want. Here are the directions from the link provided:

 

Pausing a device blocks it from accessing the internet when connected to your home network. In-progress activity might not stop immediately. Access to local network devices (like printers) and connections that use cellular data or other WiFi networks won't be paused.

To pause a device:

1. Select the device from Connect.
2. Select Pause Device.
   • You can pause the device(s) for a specific amount of time (for example, 30 minutes, one hour or two hours) or indefinitely until you choose to unpause.
     
     

Note: The pause function only pauses WiFi access on your home network and does not impact access to using cellular data, a public Xfinity WiFi hotspot or other available WiFi networks. When attempting to access the internet on a paused device, the user will see the device's default message that the site cannot be reached or that it is not connected to the internet.

To unpause a device:

1. Select the device from Connect.
2. Select Unpause Device.