it somewhat simple, i can't recall too much but lemme try, you take the PowerPoint file and upload it onto onedrive, when uploaded via i think some sort of context menu there should be some sort of embed button somewhere, maybe in a share tab? idk
but you get the embed url of your game and paste that onto a new html file.
Only issue is that hyperlinks might bug out a bit and anything VBA-related will simply just not work.
If you have any questions, just ask, i'll try answer them next time I check itch.io