Are you looking for a screw terminal, 16 or 32 of them, right on top of the HD module? (Just like the 2/4 channel modules?)
If so, interesting idea.... not sure how you'd fit them, but interesting idea.....
Regarding if the connector is a standard connector that can be purchased, the answer is yes.
Yes its standard and yes you can buy them.
Take a look at page 11 and page 13 of the High Density Digital Module Data Sheet.
On those pages, there is a section 'Building your own wiring harness for a xx module'.
It has the Molex part numbers for the connector and the pins.
At the hospital, we ran the Opto cables from the HD modules to the screw terminals in the cabinets.
The field wiring was then terminated at that screw terminal strip.
(Most of our panels were made in the panel shop, so every SNAP module was wired back to this screw terminal strip, no matter what density or type).
The building field wiring was run back to the location of the panel and then fit off once the cabinet was installed.
So, it did not matter if it was HD or standard SNAP... In fact, it was quicker if it was HD because at least with that module, its just plug and go on one end.
Of course that's just how we did it, there are a bunch of different ways, and one is probably no more right or efficient than the other.