AirTags do require network activity for the location to be make its way back to your phone, with that network activity provided by another Apple device, rather than the tag itself. And, each AirTag must be linked to an Apple account. If you find an AirTag, hold your phone near and it will give you the full serial number and the last four digits of the phone number associated with it. I’m sure Apple has all sorts of additional information, related to that account, that could be given to the authorities.