Sorry, but I have read this topic a few times and I’m still unclear on the requirements. It might be that what you want is already possible.
I get that you have a collection of PowerPoint files.
It might be that what you are looking for is adding the file type to your Admin - Settings, so that you can upload them to a post.
Or it may be that you are wanting to link to the file hosted elsewhere and have them oneboxed.
I think the first step is to add the file type to the allowed types setting and upload a smaller weight one to a post.
I’m guessing the post would show as an attached file link, but maybe with luck it will display
I think important considerations include not only the file type, but also weight and dimensions. If the average file weight is in the mega MB range it might be better to off-site them. If the average dimensions are greater than what would fit into a post it might be better to have link or preview image that would open the file in a visitors player.