It won't work, because most people do not understand what a digital signature is and they will just say that has been faked as well.
And annoyed and suspicious techies can use it to check other people's content and report them as fake.
Yeah, there are a lot of dumb people who want to be deceived. But would be good for the rest of us to have some tools.
And this is the crux of the issue - we are beelining to a world where EVERYTHING gets an AI filter in front of it. In a few years there will be no authentic content at all.