Never ran across anything but I like your idea.
Would it be possible to make your own using the
dowel centers you show if the end of a domino were
drilled out and fit the dowel center into the domino.
Sounds like a good CNC project. You might have yourself
a product in the making.
The only argument I can see against them is the Domino machine
lets you select a normal or tight width domino mortise or a wide
mortise that allows for a slight misalignment, so is this really
necessary will be what many people will ask themselves.