iPad

Apple cannot (and will not) assist with reuniting a lost device with its owner. Unless a found device has an active network connection - and the owner has marked the device as lost with a visible message on-screen, you’ll not be able to identify the owner or any contact information.

The best advice that can be offered is that you hand the device to your local authorities - along with a description of where and when the device was found. Alternatively, if found at a public transport hub, they will likely have a lost a found department with whom you can deposit the found item.