Would a camera made for the D6 Agfa roll film agree with an adapted 120 roll, via typical spacer solutions, or other?
In other words, is the D6 pretty much the same as what was the 116?
You can find 70mm film and roll your own but it will probably have perforations. You just need to get a 116 or 616 spool with some backing paper. I have never used the adapters but it seems people get good results with them, not sure how the film stays flat.
I wonder why there was that german D-6 designation at all, moreover why Agfa designated film that way (as the OP indicated), as there seem no respective cameras in the German speaking Agfa markets.1
For their foreign markets the Kodak designation seems more appropriate.
The historical rivalry and conflict of Ansco-Agfa with Kodak, perhaps?
Incidentally, I read an account of the early Ansco, by an employee, a young lad at the time, his work in the Paper lab. Worth a read:
"Ansco Reminiscences" https://scholarworks.rit.edu/article/458/
(it mentions coffee as a developer aid, as they experimented with a lot of stuff!)