AK bayonets are not what most of us consider a high-quality knife. They're sharpened more like one blade of a scissors than a knife. No idea if the steel will even hold THAT obtuse edge, let alone if you ground it to a real slicing or chopping edge. But for $12 or whatever they cost, you can get one and beat on it and see how it holds up.
I've got several (Romanian -47 style, Bulgarian -74 style) and have never been tempted to cut anything with them.
I think even a Glock field knife is a better blade, and that's saying something.
For about the same money you could get a Mora and have a real knife.