That's a difficult case, because it's a dedicated device and not a general-purpose computer. Adding a screen reader to such a device could be costly. Of course, these days, even a lot of "embedded" projects use Linux, some embedded flavor of Windows (previously CE, now Windows IoT Core), or even Android. Still, the device would need audio output. And to really cover the bases, for deaf-blind people, it would need to connect to a braille device via USB or Bluetooth.

In my ideal world, all user interfaces would run on the user's main portable computer (currently a smartphone), controlling devices remotely over Bluetooth, NFC, or the like. Embedded UIs would then be a thing of the past, and accessibility would simply be a matter of following the recommended practices for mainstream general-purpose platforms.