The smallest Echo device yet, the Flex even has it's own accessories, including a motion sensor and smart nightlight. Both are just $14 and also up for preorder. The only downside is the add-ons use up your USB port.
The Echo Flex also has microphones and a speaker inside, but don't expect music-quality sound. Given the device's size, it's most likely a just a small tweeter. But with that compactness brings the flexibility to find a home for this in any room.
I'm eager to go hands-on soon. You can pre-order it now for $24.99 from Amazon.