Apple's Find My network lets certified third-party accessories appear in the Find My app alongside AirTags. Apple itself sells only one AirTag SKU/form factor, but certified third parties can launch many certified SKUs across form factors Apple doesn't offer.
Because certification is a one-time technical/program requirement rather than a form-factor restriction, a brand can reuse the same certification path to launch new form factors (cards, fobs, passport covers) as separate SKUs, capturing form-factor-specific demand that Apple's single SKU leaves unaddressed.
A Find My-certified tracker brand expanded from card-shaped trackers to a passport cover/holder tracker, each a distinct certified SKU, unlike Apple's single-SKU AirTag.