Replacing an Airpod

Hello! I need to replace one of the AirPods I have since it has been lost (it is the ones from the first generations, 2017 i believe). The problem is I cannot locate a serial number as the device the airpods are connected to is an android. I have no way of connecting it to an iPhone since I had given it to a relative who lives a bit far. My relative says he does not find any physical writing on the airpods and i've long since gotten rid of the original packaging. Please help, and thank you.