How can I add my airpods to my devices list so I can locate it if lost

From the article below.

 If you already set up Find My [device] with an iPhone, iPad, or iPod touch that you’re using with your AirPods, it's automatically enabled for your AirPods too.

Find My Phone - Lost AirPods.  

AirPods are not a device tracked at that level. In to do, that they would need their own GPS module, which they don't have.

"My devices" are devices you sign in using your Apple ID.

Check your Apple ID device list to see where you're signed in - Apple Support