Unfortunately, the AirTags do not have a hole for a key fob. However, you should be able to drill this yourself.
Attach AirTags to the key without accessories
Apple’s little trackers, the AirTags, are on the market and I’ve already thrown one of these little UWB Smarties in my wallet. It also works really well and so hopefully it will come to an end that I often turn the apartment upside down to look for my wallet.
However, if you want to use the AirTags to attach them to your key, you will encounter a small problem after delivery. An AirTag has neither a hole for attaching a key ring, nor are any kind of accessories for this purpose included in the scope of delivery.
So you have to order an extra bracket, which, depending on the manufacturer, is either very expensive or inexpensive and therefore has an extremely long delivery time.
The colleagues from iFixit presents. They dismantled an AirTag and found that there was enough space inside to “simply” drill a hole for a key ring yourself. Ok, you have to pay attention to a little something and not go ahead and drill happily. So you have to remove the battery beforehand and then make sure to drill in the right place so as not to damage anything inside. Of course, this measure also means that an AirTag loses its watertightness and any warranty claims.