Hi Brian,
If it were me, I would focus on two things: accessibility and ease-of-use. Ensuring your documents meet accessibility requirements is hard: there is lots to worry about (heading levels, math in a screen reader, contrast) which can all be done with other software, but PreTeXt does almost all the heavy lifting for you so you can focus on the content. Recent new features allow you to embed a pretext webpage in your LMS, either as an iframe from a public website or using SCORM if you want to keep the content private to your class, so you can meet accessibility requirements easily. In terms of ease-of-use, both writing and "compiling" pretext is now no more difficult than doing so for LaTeX.
Of course, showing interactive features also always gets people excited.
Thanks for giving this talk!