(OP here). In practice my stress level about this (for me and my family) is about zero. Eight year olds are quite smart; he knows exactly what is going on here and finds it entertaining. Real dad’s presence isn’t going anywhere. It’s largely a fun gimmick and treated as such. And if it started getting weird, I’d just turn it off.

Now, as the tech improves I think this line of thinking is going to be a legitimate concern - I don’t think you are being a wet blanket. But at its current level, it’s pretty transparently a half-baked computer program, and treated as such by my kid.