Finally!¹ My biggest use case is not actually creating passes for services which don’t provide them, but being able to create passes without having to install a freaking app.
FlixBus (I might be misremembering) is the only service I ever found which lets you pay with Apple Pay and add a pass to Wallet all from Safari. For airlines and other bus/train services I always have to install the app to do both. Maybe this will allow me to buy tickets on the web then make my own pass.
¹ Assuming I even update to iOS 27, though.