Actually I think I saw where someone tried it a few years ago but I'm not sure if there's a video or notI could definitely supply you with straight and usable flakes. What I'd do would be to glue the flakes to a blade and then secure that in the shaver of choice. Hmmmm, that would be a shave video for sure and it would be quite the talk of the shaving community as you'd probably be the first to try something like that.
Edit: quick YouTube search found 3 videos of people Shaving with obsidian flakes. Still curious to try it though