Apple already does laser engraving for products bought in the online store. For the price point of this thing, they can probably move engraving into the retail stores (not long ago, I bought a laser engraver for my hobby 3D printer for a few hundred bucks -- they're not expensive, certainly not by Apple Store standards).

As for getting lost, Apple already has their AirTag technology. While I don't know if that's already in these lenses, it doesn't seem like it'd be difficult to add.