If you don't know how to scan a lost airtag on android then you must follow these steps:-
1. The first step is to take the AirTag and put it backside on your phone.
2. Then properly place the AirTag against the NFC reader.
3. Now your phone will show a pop-up menu or automatically launch a webpage.
4. Then finally you'll be able to see the contact number of the owner or a message the owner has entered if the AirTag is marked as lost.