Hi w211846943 We were working with students on an open education project not long ago and had to simply turn PPT presentations they created into videos for publishing in a Pressbooks format. We were able to use the directions here to save the PPT directly as a video, Turn your presentation into a video - PowerPoint . It just makes a video slide show but it worked for our needs. As @klundstrum suggested, there are lots of options for recording audio on PowerPoint slides or creating a screencast if you something like this.
All the best!