Hi David
It is a pleasure to get your help and suggestions!
And I am very interested in your work. If you report elsewhere, please add a link to this topic.
I just ordered two 7 inch displays, now that I see a good chance to control them with my Arduinos.
The Waveshare 7" even has selectable SPI or parallel interface, and the pinout seems very similar to the RobotDyn 2.8
Jean-Marc