A new support document from Apple reveals that any NFC-capable device will be able to ‘read’ the pre-programmed discovery message of an AirTag in Lost Mode.
NFC functionality is a part of the newly revealed Apple AirTags during the April 20 ‘Spring Loaded’ event. Apple demonstrates that people can get and tap the white button in a lost AirTag, which will redirect them to a webpage that shows the owner’s phone number.

In setting up an AirTag an owner must provide his or her information. Then, when the AirTag is in Lost Mode the details will come up so it can get back to its owner.
AirTags is a small and convenient tracker device that has Ultra Wideband and NFC. It’s powered by a U1 chip and sends out pulses to other U1 equipped devices, including the iPhone. The accessory also uses Bluetooth to communicate with other Apple devices and to check the Find My network.