Unfortunately this is a question you need to ask smartphone manufacturers, we can not share information that is not already public.
In any case keep in mind that the antenna arrays needed for Direction Finding are quite large, and with the size and complexity of modern smartphones it might not be possible, or possible with a satisfactory user experience. AoA transmitter should not be a problem though as it does not need any HW changes other than the radio IC being able to append the CTE. In this case it might still be possible to make the AoA receiver or a location system send the position to be displayed on the phone (AoA transmitter), but the phone would not know which direction it is pointing in.
