There's a lot to unpack here - basically, this question is unanswerable and doesn't really make sense unless we know the actual context. What are you actually trying to do?
First of all, auditors audit to something - so the answer depends on what auditor. Is it an ISO 13485 Auditor? Then they're not going to audit you to FDA requirements. At most, they'll suggest that you should consider those requirements.
An MDSAP Audit with the USA in scope? It covers FDA requirements, and you'd be held to those requirements. You could be asked about any part of them.
By "from a design perspective", I'm not sure what you mean. 21 CFR 820 is a quality system regulation.
Unless you can provide more detail on what you're trying to accomplish, I would recommend looking at the MDSAP Audit model. It's available online, and is used to audit to 13485, 21 CFR 820 and some other regional requirements - probably the closest you'll get to seeing what a typical quality system audit might look at.
Now, putting the product into market is an entirely different beast from setting up a quality system. Anyone who sees that you've marketed a device without clearance is not going to be asking you audit questions, they'll be getting in contact with the authorities - knowing what an auditor would ask is irrelevant; have market clearance before you market your device.