When Apple released the first beta of iOS 12, it was identified that the 2012 redesign of the AirPort Express appears in the Home app, although it was not possible to add the device as a HomeKit peripheral. The second beta of iOS 12, however, goes beyond just discovering the AirPort Express in the Home app, as noted by AppleInsider.
The source believes that iOS 12 may actually add AirPlay 2 capabilities to the now discontinued AirPort Express. In iOS 12 beta 2, the Home app shows an alert that an AirPort Express update is available and needs to be applied. But since no update is yet available, the Home app fails in the same manner as it did in the first iOS 12 beta.
The updated process in iOS 12 is, however, the best sign that the AirPort Express may be added as an AirPlay 2 compatible bridge for wired speakers.
“The last update to the AirPort express was in December 2017, for the KRACK exploits from earlier in the year. AirPlay 2 wasn’t in testing at the time, with the AirPort patch happening well after the first round of testing of the technology, and before the abortive second round with the iOS 11.3 betas prior to its removal very near the end of the cycle.
This is now the third time that the AirPort Express has appeared as a HomeKit accessory and potential future AirPlay 2 target, and done nothing when selected. It was pulled about two weeks after the first iOS 11.4 beta.”
It must be kept in mind that support for AirPlay 2 in AirPort Express can in no way be guaranteed at this point.