One advantage could be the sales channel. Through Apple store they can easily get the products into the hand of customers. This might be quite valuable with products which you need to experience in order to understand them.

Apple's share of mobile phone market can be helpful if they want to bring in functionality that requires special features from the handset.

Also if we think about some more down to earth stuff, Apple could become "number one AR vendor" by just putting the features to next iPhone models. If the stuff actually works and if Apple allows, this might bring in 3rd party developers.