Is it a product that is similar enough to an existing product that it will meet the same Acceptance Criteria (AC), which is basically the ICC defined rules for how they will test/rate/document the product? For example, for post installed concrete expansion bolts, there are a number of examples of similar products already with ICC reports. But if the product doesn't have a similar AC to compare to, developing the AC would likely be the first step, and can be a real challenge. And staying current for ICC-ESR approval is an involved process, including site inspections of fabrication facilities, periodic testing and lots of documentation.
In my personal experience, the ICC can be challenging to work with, to the point where many groups are now using other agencies (i.e. IAPMO) to conduct and manage the evaluation process, and create their own reports (see Hilti HST3 for an example). I believe that there was/is a court case between ICC and some of these other evaluation agencies, though I don't know if I know the final result.
But regardless, it is generally not a simple or straight-forward process. I was tangently involved in the process for a product with a new AC, that was several years before approval was reached.
