[tmm84]

You don't sound like you really want to be a part of these companies your preparing to interview at by saying "Heck I didn't even apply for these jobs.". And you seem to be having trouble finding a good reason to really go to the interview. The more I read your post; the more I feel that you don't want to feel stupid or inadequate based on the interview. Everyone doesn't want to feel stupid or inadequate, this is normal. Also you've put the interviews on a pedestal that'll declare you as good enough by discounting your experience and achievements thus far.

If you feel this wound up before the interview how do you think you'll feel working for these two companies? It'll be a daily anxiety/fear of being inadequate for the job.

My advice is to lower your expectation/valuation of the interviewing company and go to the interview if you really deep down inside want to. These kinds of interviews have a history of making interviewees feel worse about themselves so bear that in mind.