We have not been thru a GRMA (partially GFSI sanctioned) audit and having looked thru the GRMA organization we will also not be requiring any of our supplement, OTC, CBD, etc suppliers to have a GRMA.
If you have a NSF audit that is suited to supplements etc I see NO reason why a customer would want to add a redundant certification audit, that would be number one and the other is the fact that the operating board President and another 1 or 2 people is involved in Big Pharma.
We had looked into GRMA as we had an interest in consulting on the program (way back when) but after taking a close look at them we decided to not go to the expenses involved and did not align with the need for them.