We have a desktop app communicating with the running PowerPoint app through COM (using NetOffice wrapper) which is able to create, modify slides and shapes in the opened document by calling COM methods. We also have a modern JS-based content add-in, which we would like to configure and insert to a specific slide from that desktop app (like a standard shape). I went through the entire object model documentation, but didn't find anything regarding the content add-ins.
So, my question is: It is somehow possible to insert a modern/JS PowerPoint content add-in (or even install it if missing to PowerPoint) using the COM/PIA API?
No, the PowerPoint extensibility model doesn't provide anything for that.