It could be worth looking into standards like https://h5p.org/ (content created with Lumi Desktop for example)
Just finished going through the course. I didn’t do it in one sitting, but I will try to put all my thoughts together the best I can.
My most common annoyance was, highlighted text is less readable in dark mode. I am using Dark Reader extension. Looks fine in light mode.
In regards to content, It is very to the point and provides relent information, expands on each point well.
I found quizzes to be easy. Perhaps they should be?
It might just be my familiarity with the topic made it very obvious what the right answers were.
The last part where we create our own thread model is a good touch. I think it will benefit from sample threat models to show case how in different situations or circumstances, measures taken should be different.