How an audit runs.
You tell me the product and the one scenario your customers run most. I sign up like a stranger, set it up from the docs alone, run the scenario from a clean state until it breaks or holds, and keep a network capture running throughout. About two weeks later you have a findings report, a short list of questions a careful buyer would ask you, and one retest round for whatever you fix.
One product, one scenario, agreed in writing before I start.
Blank workspace, docs only. Steps the docs skip get written down.
Clean state each time, network capture on, a timestamp on each step.
Severity, reproduction steps, screenshots, questions for your team. Then a retest.