I wanted to provide more observations about the alpha prototypes.
The dot matrix is different, and I’ve referred to it as the “alpha pattern” in this thread.
I have been using this triangle and these two pairs of dots as a quick way to identify it.
There is a pattern to the dots, and it repeats on a diagonal.
If you rotate the pattern 90 degrees, you get this 16x24 pattern that repeats across the page.
There is a dissertation that breaks down different dot patterns: https://www.researchgate.net/publication/325976319_Reverse_Engineering_the_Machine_Identification_Code
The alpha pattern matches the “Corner” pattern in this paper, you can see the “corner” in the top left grid above. As mentioned, this is the pattern produced by Konica Minolta (Japanese brand) and some Epson printers.
Placing the alpha pattern on top reveals they match.
This paper also mentions this pattern: https://dl.acm.org/doi/10.1145/3206004.3206019
It seems like this pattern has not been broken publicly. Both papers conclude there is likely no time information encoded, but presumably you could get the model number and check when the model was released.
This may be as far as I can take it. If US Federal law enforcement decides this is important enough, they have the potential to request the company to decode it. A Freedom of Information Request has revealed that they have a working relationship with Konica Minolta (or, at least the two separate companies before they merged):