WRT to the tag placement, one user wrote that he put his airtag inside the stem (Airtags are 1.23 inch in diameter, so they won't fit inside a typical steerer, but they just might inside your stem).

Problem is that pros carry battery-powered grinders that can defeat any lock in a matter of seconds. So I would think that the point is to deter the amateurs. An interesting solution might be to put a lock on a steerstopper. (scroll to the bottom). The device would be useful on its own (my bike fell more than once) and this type of lock might just work.