If I remember right YouTube already provides the tools for that and you can just outright region lock an upload (possibly depending on having the right creator bits as a studio/large channel)
Yes, for CMS channels, which would be your movie studios, TV studios, etc. They have an option to block certain countries from watching it. If you are around in YouTube often enough you will find a video or two that will say something like "this video isn't available in your region/country"