[mfkp]

Lithium batteries with you in the cabin have different rules than lithium batteries inside checked luggage.

Also cell phones don't need to be powered off while inside the cabin.

[rockemsockem]

Air tags don't use lithium batteries. They use the big, flat, circular batteries that you have to replace.

[mfkp]

Airtags use a CR2032 lithium battery: https://support.apple.com/en-us/HT211670

The FAA specifies both lithium ion and lithium metal batteries need to be in carry-on bags only, not checked: https://www.faa.gov/hazmat/packsafe/more_info/?hazmat=7

[nonethewiser]

So they dont let you check watches?