Converting Adobe Express videos to Powerpoint presentations

I have a Youtube channel with monthly short (4 min) videos on Global issues created with Adobe Express (formerly Adobe Spark) using background music. I need to convert these to 45 minute Powerpoint presentations with a narrated soundtrack - that would extend the video to say 45 minutes. My 4 minute Spark videos will not change for some time - I don’t need help on them, it is the conversion process from Spark (Express) to Powerpoint I need assistance on and in particular using narration not background music . My videos are mostly colourful images superimposed by large text displayed for between 5 and 12 seconds against the background of continuous dramatic music. I am an experienced narrator and presenter, no problem there but how do I plan it all out ? In other words at this stage I am not looking for a video/animation/motion graphics expert at all but someone with experience, patience, who listens carefully to what is asked and a good clear voice who can patiently guide me through the steps I need to take - however long it takes. So my main requirement is adapting the Adobe Spark video into a narrated Powerpoint presentation.. Narration and voiceover completely by me. An important point is: can I convert direct from Adobe Express Video to Powerpoint or do I have to go via Adobe Express Post? You can do narration on Adobe Express but it is not right for the material. Best to think I am moving from a fairly punching video to a general audience to a long one for an academic level audience