Well I tried to convert an exe into a pptx and it outputted a file that looked like an attempt at html, saying that the conversion wasn't feasible due to its nature and size
I mean the website cays it can convert anything to anything ("every file exists as all file types all of the time") so it should be able to do exe to pptx
Based on important research like https://www.youtube.com/watch?v=uNjxe8ShM-8, it should definitely be possible to generate a .pptx that will run Windows inside of an emulator inside PowerPoint slides. That HTML file is lying to you!