I did get burned on a few interviews where I claimed to know C and then they asked some difficult pointer questions that were out of my depth. Truth was I had done C++ and a little bit of C in one class but not much. So you need to be able to pass a verbal interview and a coding interview.
If I were you I would also suggest not trying to get a job in one of those sub-fields right away, but instead look for any decent software job, get some experience, then look to move into a niche area.