They likely went with this form factor because it allows for the camera to look forward and use that context in its responses. A watch wouldn't easily be able to do this.
And then you could do video calls on the same device too.
Anyway, it's cold season now in Europe, and it's interesting how much less useful my Apple watch is when it's almost always covered with a sleeve.
Something that goes on top of your clothes makes sense.
I for one have no particular desire to be part of your "context" (nor the company's training data set) without knowing it.