Face shields, PERIOD, are going to be tough to find right now due to the COVID-19 outbreak. People are looking for ANY sort of protection, even if it's meager.
You can try to make your own face shield if you have a 3D printer, but some of the raw materials are tough to get your hands on.
As for potentially breaking the skin, well...Why do dentists wear face shields when working on someone's teeth and doing drilling? Stuff gets thrown up from it, and it can get all over your skin or potentially hurt. I used to cut out pieces of emu and ostrich eggs with a Dremel tool for a friend of the family - she would decorate them and sell them as "faux Faberge eggs" - they were really intricate works of art, and she made a good living selling them. Well, I had several pieces of egg get thrown up into my face, and on occasion, I'd end up with a scratch or two - and that was with an eggshell.
With high enough velocity and pressure, anything can cut you. A broken Dremel cutoff wheel might or might not have enough force to cut you - but ultimately, do you want to take the chance? I'd honestly say it's better to be safe than sorry.