Now that you recognize that your organization already works as a system to sustain itself by creating and satisfying paying customers (sometimes disguised as a mission statement) you may develop that system so everyone knows how it works and can see what needs to be improved.
Even though you may use your auditing skillls to do this I wouldn’t call it an audit or even a gap analysis.
Better to engage top management in determining the processes that are essential to their system for understanding customer needs, translating those needs into requirements, fulfilling the requirements and obtaining prompt payment to invest in improvement. Those processes that comprise the value stream are supported and directed by other processes in the system such as strategic planning, maintaining facilities and equipment, recruiting, training, purchasing, auditing and investing in improvement.
Ask top management to assign each process to the person best qualified to be its “owner”. With each process owner seek to understand how the inputs of data, information and materials are known to be valid, how value is added and that the results can be relied upon. You could record such facts in deployment flowcharts which could become the documented procedures where none already exist. Capture the “as-is”, and have the process owners arrange reviews for accuracy.
Then you can use your knowledge of the system standard to initiate discussion about the benefits of corrective action as and if required.
So, as you can see, developing the system you’re already part of is preferable to you suggesting that you are trying to impose something new “from ISO” via an audit.