lost iPad doesn't show on a list of devices

To further clarify your earlier post…

Lost iPad doesn't show on a list of my de… - Apple Community

… start here:

Locate a device in Find My on iPad - Apple Support

Here is Apple’s advice for lost or stolen devices:

If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

Use the Find My app to locate a lost or stolen device – Apple Support

If the Find My iPad feature was enabled prior to it being “misplaced”, then if active, you would stand a good chance of locating it. 

However, if the feature was not activated prior to being misplaced - or the iPad has been inactive for more than 24 hours, the last known location will not be available - and the opportunity to use technical means to recover the iPad have been lost.

Then you can’t track or erase it.

Find My needs to be activated on the device before it’s lost or stolen.