Both AirTag and iPhone lost
Since both AirTag and (the paired) iPhone stolen, can I get another iPhone, sign-in with the same iCloud account and track the AirTag?
Question marked as
Yes.
AirTags are actually paired w/ the AppleID via your iPhone.
So a replacement iPhone (or iPad or Mac) using the same AppleID can possibly locate the the AirTag using FindMy.
(If it’s technically “locatable”)