I missed the announcement about Apple Air Tags. First I’ve heard of them.
We’ve been using similar devices since Christmas - Tile Mate trackers. They come in different types - chips with a loop that you can put on a keyring, flat credit-card-shaped ones that you can put in a wallet, and sticky ones that you can attach to objects. We haven’t stuck any to our bikes yet, but they work well for finding our keys.
Sounds like they work exactly like the air tags. You have to be within bluetooth range (about 100 m) to activate the device, and it will show on a map where the tile was last detected (although for some reason my phone thought one of our tiles was in the back yard, when it was in my pocket). However, if another tile user passes by the tile and detects it, it can be shown on a map, so it might be possible to track down a stolen item. Sounds like the air tags work the same way, but might be better since the Apple Find app will be running on most users phones, whereas there are fewer tile users.